Massachusetts Department
Of
Public Health

Bureau of Environmental Health Assessment,
Community Assessment Program

Assessment of Brain and Central
Nervous System Cancer Incidence
in Needham, MA
1987-1998

December, 2002

Assessment of Brain and Central Nervous System  
Cancer Incidence in Needham, MA
1987-1998

TABLE OF CONTENTS

I.  INTRODUCTION ..................................................................................................................... 1  

II.  OBJECTIVES................................................................................................................................. 1  

III.  METHODS FOR ANALYZING CANCER INCIDENCE .................................................... 3  

A.  Case Identification.............................................................................................. ......................3  
B.  Calculation of Standardized Incidence Ratios (SIRs)................................................................3  

C.  Calculation of 95% Confidence Interval ...................................................................................5  
D.  Evaluation of Risk Factor Information ......................................................................................6  
E.  Determination of Geographic Distribution .................................................................................6  

IV.  METHODS FOR ASSESSING ENVIRONMENTAL INFORMATION................................7  

V.  RESULTS OF CANCER INCIDENCE ANALYSIS............................................................... 7  

A.  1987-1998 (Table 1) .............................................................................................. ...................8  
B.  1987-1993 (Table 2) .............................................................................................. ...................9  

C.  1994-1998 (Table 3) .............................................................................................. ...................9  

VI.  RESULTS OF ANALYSIS OF RISK FACTOR INFORMATION.......................................10  

A.  Histology ......................................................................................................... ........................10  
B.  Gender and Age..................................................................................................... ...................11  

C.  Race............................................................................................................... ...........................12  
D.  Occupation........................................................................................................ .......................13  

VII.  GEOGRAPHIC DISTRIBUTION.........................................................................................13  

VIII.  AVAILABLE ENVIRONMENTAL INFORMATION AND CANCER INCIDENCE .....15  

IX. DISC USSION................................................................................................ .........................18  

X. CONCL USIONS................................................................................................. .....................19  

XI. RECOMMEN DATIONS........................................................................................... .............20  

i

I. INTRODUCTION  

At the request of the Needham  Health Department, the Community Assessment Program  
(CAP) of the Massachusetts Department of Public Health, Bureau of  Environmental Health  
Assessment (MDPH, BEHA) conducted an evaluation of the incidence of brain and other  
central nervous system (CNS) cancers in the town of Needham, Massachusetts.  Recent data  
from the Massachusetts Cancer Registry’s (MCR’s) regularly published report  Cancer  
Incidence in Massachusetts: City and Town Supplement , which provides incidence data for  
each city and town in Massachusetts for 23 different types of cancer, indicated that the  
incidence of brain and CNS cancers was statistically significantly elevated in the town of  
Needham for the time period 1994-1998 com pared to what would have been expected based  
on statewide rates of this disease (MDPH, 2001).  In response to these findings and general  
environmental concerns voiced by the Needham  Health Department, the CAP initiated a  
further examination of the pattern of brain  and CNS cancer incidence in Needham .  This  
report reviews the pattern of brain and CNS cancer incidence in the town of Needham and by  
smaller geographic area for each of its five census tracts during the time period 1987-1998  
and two smaller time periods: 1987-1993 and  1994-1998.  This report also examines  
available data on risk factors that may play a role in the development of these cancers.  

II. OBJECTIVES  

This analysis provides a descriptive evaluation of the occurrence of brain and CNS cancers in  
the town of Needham  with respect to time of diagnosis, age at diagnosis, gender, and  
geographic distribution of the places of residence for individuals diagnosed with these cancer  
types.  It provides a comparison of the incidence of brain and CNS cancers in Needham  with  
respect to the incidence of these cancers in the Commonwealth of Massachusetts as a whole.  
Additionally, available information about factors  that may be related to the development of  
brain and/or CNS cancers was evaluated.  

The results of a descriptive analysis, such as the evaluation presented here, cannot be used to 
establish a causal link between a particular risk factor and a disease outcome, like brain  
and/or CNS cancer.  However, the results of this analysis m ay be useful in determining if a common etiology (i.e., cause) of brain or CNS cancer in individuals residing in Needham  is  
possible.  The results m ay also be helpful in identifying areas in Needham  where further  
public health investigations or actions m ay be warranted.  Such actions may include follow- 
up environmental investigations or public health interventions.  The purpose of this  
evaluation is to report our findings on the pattern of brain and CNS cancers in Needham  and  
discuss them in the context of the available  scientific and medical information about these  
diseases to determine whether further public health action is warranted.  

The specific objectives of this investigation were as follows:  

•	To examine the incidence of brain and CNS cancers in Needham  by smaller geographic  areas and to determine if certain areas in the town may have higher or lower rates of brain and CNS cancers;  

•	To evaluate the geographic distribution and spatial patterns of individuals diagnosed with  brain or CNS cancers in order to determine  whether an atypical geographic pattern of  individuals diagnosed with these exists in certain areas of Needham;  

•	To review available information for characteristics of the Needham  population that could  suggest risk factors for the development of brain and/or CNS cancer;  

•	To evaluate the temporal (i.e., time) distribution of brain and CNS cancer diagnoses in  Needham to determine if the incidence of these cancers has changed over time;  

•	To review existing environmental information for hazardous waste sites located in  Needham and other sites of environmental  concern to determine the likelihood that  potential environmental exposures could play  a role in the pattern of brain and CNS  cancer incidence in Needham;  

•	To interpret the results of this evaluation in the context of available scientific evidence on  brain and/or CNS cancer and to provide a clearer understanding of any patterns of disease  in order to decide whether further public health actions are warranted.  

III.  METHODS FOR ANALYZ ING CANCER INCIDENCE  

A. Case  Identification  

The observed number of individuals diagnosed with brain and/or CNS cancers in this  
evaluation was obtained from the MCR, a division of the MDPH Bureau of  Health Statistics  
Research and Evaluation.  In 1982, the MCR began collecting information on individuals  
diagnosed with cancer in Massachusetts.  All newly diagnosed cancer cases are required by  
law to be reported to the MCR within six  months of the date of diagnosis (M.G.L.  
c.111s.111B).  The seventeen-year period 1982- 1998 constitutes the period for which the  
most recent and complete cancer incidence data were available at the time of this analysis.  

The term “cancer” is used to describe a variety  of diseases associated with abnormal cell and  
tissue growth.  Primary site (location in the body where the disease originated) and histology  
(tissue or cell type) classify the different  cancer types.  Epidemiological studies have  
revealed that different types of cancer are individual diseases with separate causes, risk  
factors, characteristics, and patterns of survival (Preston-Martin & Mack, 1996).  Only  
primary site brain or CNS cancers were included in this evaluation.  The brain is a common  
site for the spread or metastasis of cancer  from another area within the body.  Brain or CNS  
cancers that occur as the result of metastasis, or the spread of a primary site cancer to another  
location in the body, are considered as separate  cancers and were, therefore, not included in  
this evaluation.  

B.  Calculation of Standardized Incidence Ratios (SIRs)  

In order to determine whether an unusual occurrence of brain and/or CNS cancer exists in  
Needham as a whole or census tracts within Needham, cancer incidence data were analyzed  
by age-group and gender.  These two criteria we re used to com pare the observed number of  
cancer cases in each Needham  census tract to the number that would be expected based on  
the incidence of brain and CNS cancers in Massachusetts as a whole.  Standardized incidence  
ratios (SIRs) were calculated for brain and  CNS cancers for the town of Needham  and each  
of the five census tracts that geographically  subdivide the town for the 12-year time period  
1987-1998 and two smaller time periods (1987-1993, 1994-1998).  This year range was  selected based on the elevation in brain and CNS cancer in Needham  noted by the MCR and  
the Needham Health Department.  

Because age-group and gender specific population data are needed to calculate incidence 
rates, the census tract (CT) is the smallest geographic area for which cancer rates can be  
accurately calculated.  Specifically, a CT is a smaller statistical subdivision of a city or town.  
Census tracts usually contain between 2,500  and 8,000 persons and are designed to be  
homogenous (i.e., the same throughout) with respect to population characteristics (U.S.  
Department of Commerce 1990).  Needham  is comprised of five CTs: 4031, 4032, 4033,  
4034, and 4035.  The geographic location and boundaries of Needham  as well as the CTs  
located in Needham are presented in Figure 1.  

An SIR is an estimate of the occurrence of cancer in a population relative to what might be  
expected if the population had the same cancer experience as some larger comparison  
population designated as “norm al” or average.  Usually, the Commonwealth as a whole is  
selected to be the comparison population.  Using the Commonwealth of Massachusetts as a  
comparison provides a stable population base for the calculation of incidence rates.  

Specifically, an SIR is the ratio of the observed number of cancer cases to the expected  
number of cases multiplied by 100.  An SIR of 100 indicates that the number of cancer cases  
that is observed in the population being evaluated is equal to the number of cancer cases  
expected based on state-wide incidence rates.  An SIR greater than 100 indicates that m ore  
cancer cases occurred than were expected and an SIR less than 100 indicates that fewer 
cancer cases occurred than were expected.  Accordingly, an SIR of 150 is interpreted as 50%  
more cases than the expected number; an SIR of 90 indicates 10% fewer cases occurred than  
were expected.  

Caution should be exercised, however, when interpreting an SIR because the interpretation  
depends on both the size and stability of  the SIR.  Two SIRs can have the same size but not  
the same stability.  For example, an SIR of  150 based on four expected cases and six  
observed cases indicates a 50% excess in cancer, but the excess is actually due to only two 
cases and may be the result of chance or random  variation in cancer incidence.  Conversely,  
an SIR of 150 based on 400 expected cases and  600 observed cases represents the same 50% excess in cancer, but because the SIR is based upon a greater number of cases, the estimate is  
more stable.  It is very unlikely that 200 excess cases of cancer would occur by chance alone.  
As a result of the instability of incidence rates based on a small number of cases, SIRs are not  
calculated when fewer than five cases are observed.  

It is necessary to obtain accurate population information in order to calculate incidence rates.  
The population figures used in the analysis  for the twelve-year period of 1987-1998 and for  
the two smaller time periods (1987-1993 and 1994-1998) were mid-year population estimates  
based on the 1990 and 2000 U.S. Census data for each census tract in Needham  (U.S.  
Department of Commerce 1990, U.S. Department of Commerce 2000).  

C.  Calculation of 95% Confidence Interval 

In addition to calculating SIRs, the statistical  significance of each SIR was assessed.  A 95%  
Confidence Interval (95% CI) was calculated  for each SIR to determine if the observed  
number of brain and CNS cancer cases is significantly different from the expected number or  
if the difference m ay be due solely to chance (Rothman and Boice 1982).  A 95% CI is a  
method of assessing the magnitude and stability of  an SIR.  Specifically, a 95% CI is the  
range of estimated SIR values that have a 95%  probability of  including the true SIR f or the  
population.  If the 95% CI range does not include the value 100, then the study population is  
significantly different from the comparison or “normal” population.  “Significantly different”  
means there is a less than 5% chance that the difference between the number of observed and  
expected cancer cases is the result of random  fluctuation in the number of observed cancer  
cases.  

For example, if a confidence interval does not include 100 and the interval is above 100 (e.g.,  
105-130), then there is a statistically significant increase in the number of cancer cases.  
Similarly, if the confidence interval does not  include 100 and the interval is below 100 (e.g.,  
45-96), then the number of cancer cases is statistically significantly lower than expected.  If  
the confidence interval range includes 100, then  the true SIR m ay be 100, and it cannot be  
concluded with sufficient confidence whether the observed number of cases is the result of  
chance or whether it reflects a real increase or  decrease in the number of cases.  Statistical  
significance was not assessed when fewer than five cases were observed.  

In addition to indicating the significance of the SIR estimate, the width (or range) of the  
confidence interval also reflects the stability  of the SIR estimate.  For example, a narrow  
confidence interval (e.g., 103-115) allows a fair level of certainty that the calculated SIR is  
close to the true SIR of the population.  A wide interval (e.g., 85-450) leaves considerable  
doubt about the true SIR, which could be lower  than or higher than the calculated SIR.  A  
wide interval indicates an unstable statistic.  

D.  Evaluation of Risk Factor Information  

Through the evaluation of characteristics of the population, profiles can be constructed that  
may offer explanations for the observed patterns in the occurrence of brain and CNS cancers  
in Needham  and its CTs.  Risk factors such  as age at diagnosis, gender, occupation, and  
histology (cancer cell type) are data regularly collected by the MCR for individuals  
diagnosed with cancer.  However, information  about personal risk factors that m ay also  
influence the development of brain and/or  CNS cancers (e.g., family history and heredity,  
exposure to ionizing radiation, exposure to n-nitroso compounds, and history of head trauma)  
are not collected by the MCR or any other readily accessible source, and therefore, could not  
be evaluated in this investigation.  

E.  Determination of Geographic Distribution  

In Needham , the geographic distribution of  brain and CNS cancer cases was determined  
using available address information from  the MCR indicating residence at the time of  
diagnosis.  This information was mapped for each  individual with a diagnosis of brain or  
CNS cancer during 1987-1998 using a computerized geographic information system (GIS)  
(ESRI, 2000).  This allowed the assignment of a CT location for each case as well as a  
qualitative evaluation of the spatial distribution of  cases at a smaller geographic level within  
census tracts.  The geographic distribution was assessed using a qualitative evaluation of  the  
point pattern of cases within the town and within each CT.  In instances where the address  
information was incomplete (i.e., did not include accurate street information for Needham ),  
efforts were made to research cases using  telephone books, town residential lists, and, when  
applicable, death certificates issued within two years of an individual’s diagnosis year. 

IV.  METHODS FOR ASSESSING  ENVIRONMENTAL INFORMATION 

Because some studies have suggested a possible association between certain environmental  
exposures and the development of brain and CNS cancer, information regarding hazardous  
waste sites located in Needham  and listed with the Massachusetts Department of  
Environmental Protection (MDEP) was review ed (MDEP, 2002).  The MDEP investigates  
potentially hazardous sites in the state and conducts and oversees cleanup of these sites. 
These sites are regulated according to Massachusetts General Laws (MGL), Chapter 21E and 
the Massachusetts Contingency Plan (MCP) (contained in the Code of Massachusetts 
Regulations (CMR) at 310 CMR 40.0000).  

Needham waste sites and spills reported to  the MDEP from  1982-1993 were mapped and  
evaluated in term s of the locations of the places  of residence of individuals diagnosed with  
brain and/or CNS cancers. Brain cancer is of ten described as having a lengthy latency or  
development period, sometimes in excess of  20 years.  The latency period is the time  
between exposure to a potentially harmful substance and the development of the cancer  
(Preston-Martin & Mack 1996).  Generally, environmental spills began to be reported to  
MDEP consistently in the early 1980s.  Therefore, in order to focus on past exposures  
consistent with a latency period f or brain cancer , sites or spills reported to the MDEP from  
1982 to 1993 were reviewed.  Environmental spills that occurred after this time period are  
unlikely to result in exposures relating to brain and/or CNS cancer incidence during the 
1987-1998 period.  These sites (1982-1993) were mapped using an electronic GIS and the  
proximity of these sites to the place of residence of individuals diagnosed with brain or CNS  
cancers was assessed. 

V.  RESULTS OF CANCER INCIDENCE ANALYSIS  

Brain and CNS cancer incidence data from  the MCR was analyzed for Needham  for the  
1987-1998 time period.  To evaluate trends over  time, brain and CNS cancer incidence for  
two smaller time periods (1987-1993 and 1994-1998)  was also analyzed.  The following  
sections present the results of this evaluation for Needham  as a whole and for each census  
tract in the town.  Analysis by smaller geographic areas (i.e., census tracts) helps in understanding whether the incidence of brain  and CNS cancer observed town-wide m ay be  
due to increases in particular areas of the town.  Tables 1 through 3 summarize brain and  
CNS cancer incidence data for the town as a  whole and for each census tract during each of  
the three periods.  

A.  1987-1998 (Table 1)  

During the 1987-1998 period, brain and CNS cancers occurred about as often as expected in  
the town of Needham  as a whole for both m ales (21 observed versus about 20 expected,  
SIR=106) and fem ales (20 observed versus about 19 expected, SIR=104).  As described  
below, the overall rate observed during  the 12-year time period 1987-1998 reflected a  
statistically significantly lower-than-expected rate during 1987-1993 and a statistically 
significant elevation in the incidence of brain and CNS cancer during 1994-1998.  

Brain/CNS cancers occurred at or below expected  rates in CT 4031 (6 observed versus about  
9 expected, SIR=66), CT 4032 (5 observed versus 5.6 expected, SIR=89), and CT 4034 (7  
observed versus 11.7 expected, SIR=60).  In CT 4035, brain cancer occurred slightly m ore  
often than expected during 1987-1998 (9 observed  versus about 7 expected, SIR=127).  This  
elevation, however, was based on two additional cases above the expected number and was  
not statistically significant.  

Individuals residing in CT 4033, located in the  southern part of Needham , experienced a  
statistically significant elevation of brain and CNS cancers during the 1987-1998 period (14  
observed versus 5.5 expected, SIR=257, 95% CI=140-431).  When evaluated by gender, both  
males (6 observed versus about 3 expected, SI R=213) and females (8 observed versus about  
3 expected, SIR=304) experienced an elevation in brain and CNS cancer incidence.  The  
elevation observed in m ales in CT 4033 was not statistically significant.  However, the  
elevation observed in females was statistically significantly higher than expected.  

B.  1987-1993 (Table 2)  

During the time period 1987-1993, the incidence of  brain and CNS cancer in Needham  as a  
whole was statistically significantly lower than what would be expected for m en and women  
combined (16 observed versus about 28 expected, SIR=59, 95% CI=33-94).  When evaluated  
by census tract, both m ales and fem ales in  each individual census tract in Needham  
experienced fewer brain/CNS cancers than expected during this time period.  

C.  1994-1998 (Table 3)  

During the most recent time period, 1994-1998, brain and CNS cancer occurred statistically  
significantly more than expected in Needham  as a whole for both m ales (13 observed versus  
about 6 expected, SIR=210, 95%  CI=112-360) and fem ales (12 observed versus about 5  
expected, SIR=229, 95% CI=118-400).  

When evaluated by census tract, individuals residing in CT 4034 experienced brain and CNS  
cancer slightly lower than the expected rate (2 observed versus about 3 expected).  
Additionally, in CTs 4031 and 4032 brain and CNS cancers occurred at approximately the  
rate that would be expected (3 observed versus about 3 expected in CT 4031 and 3 observed 
versus about 2 expected in CT 4032).  However, a statistically significant elevation was  
observed in CT 4033 for brain and CNS cancer  (10 observed versus about 2 expected,  
SIR=643, 95% CI=308-1183).  When evaluated by  gender, both m ales (4 observed versus  
about 1 expected) and fem ales (6 observed versus about 1 expected, SIR=867, 95% CI=317- 
1888) in CT 4033 experienced elevations in brain and CNS cancer incidence.  The elevation  
observed among fem ales in this census tract was statistically significant.  Brain and CNS  
cancers in CT 4035, located northern part of  Needham , also occurred statistically  
significantly m ore often than expected among  males and fem ales combined for this time  
period (7 observed versus about 2 expected, SIR=330, 95% CI=132-680).  

VI.  RESULTS OF ANALYSIS OF RISK FACTOR INFORMATION  

In order to better understand the patterns of  brain and CNS cancer incidence in Needham ,  
factors that are thought to contribute to an individual’s risk for developing these types of  
cancer were evaluated.  As brain and CNS cancer are comprised of a number of different cell  
types, review of the histology (cell type ) of brain and CNS cancers diagnosed among  
residents of Needham is important to help to determine whether an atypical pattern of disease  
is occurring.  Other risk factors reviewed  include gender, age, race, and occupation.  
Specifically, brain and CNS cancers are slightly m ore common among m ales and, after a  
peak in childhood (e.g., under age 10), risk  declines slightly until around age 25, and  
increases consistently as age increases thereafter (Preston-Martin & Mack 1996).  In general,  
the highest rates of brain and central nervous  system cancers tend to occur in whites.  In  
addition, research has shown that some occupational exposures m ay increase the risk of  
developing brain and CNS cancer among individuals employed in such industries as plastics  
manufacturing, aspartame (or artificial sweetener) manufacturing, electrical work, veterinary  
or agricultural work, as well as among some workers in the nuclear and rubber industries and  
in certain health professions.  These data are collected by the MCR and are reviewed below  
for individuals diagnosed with brain and CNS  cancer in Needham .  However, risk factors  
such as heredity, consumption of nitrites and other N-nitroso com pounds found in some  
foods (e.g., cured m eats), exposure to ionizing radiation, and history of head trauma, which  
have been associated with an increased risk  of developing brain or CNS cancer in some  
studies, could not be evaluated because information related to these factors for individuals  
with brain or CNS cancer in Needham  was not available.  Therefore, the extent of the role  
these factors m ay have played in the incidence of brain and CNS cancer in Needham  in  
unclear.  For more information regarding potential risk factors for brain and CNS cancer, see  
Appendix A.  

A. Histology  

Histologic (cell type) distribution was reviewed  for diagnoses of brain and CNS cancers in  
Needham.  Patterns of disease were com pared to known or established incidence trends to assess whether any unexpected patterns exist.  Primary brain and CNS tumors (i.e., brain  
cancer) comprise two main types: gliomas and malignant meningiomas.  Gliomas are a  
general classification of m alignanttum orsth at also include a variety of subtypes.  
Meningiomas are not technically brain tumors as they arise from  the meninges, which are  
tissues that surround the outer part of the spin al cord and brain.  These tumors account for  
approximately 50% of reported brain and CN S cancers but the majority (85%) are benign  
(non-cancerous) (ACS 2002a).  In both children  and adults, gliomas are the most common  
major histologic type and over 80% of gliomas are astrocytic gliomas (i.e., astrocytomas and  
gliobastoma multiforme) (Preston-Martin and Mack 1996).  In children, about half of all  
brain and CNS cancers are astrocytomas and about 25% are medulloblastomas (ACS 2002a).  

Of the 41 individuals diagnosed with brain and CNS cancer in Needham  between 1987 and  
1998, 38 (93%) were diagnosed with brain cancer  and five were diagnosed with other CNS  
cancers (e.g., cancer of the spinal cord).  Consistent with expected trends in histology  
distribution, the majority of brain and CNS  cancers diagnosed among residents of Needham  
were gliomas (88%).  Of these 38 gliomas, 28 (74%) were astrocytomas or glioblastomas and  
10 were other glioma subtypes or were not classified as to specific subtype.  Meningiomas  
accounted for 7% (n=3) of all brain and CN S cancers in this area between 1987-1998.  All  
four of the brain and CNS cancer diagnoses  among children in Needham  were of the  
astrocytoma subtype.  

B.  Gender and Age  

Of the 41 individuals diagnosed with brain  or CNS cancer in Needham  during the years  
1987-1998, 20 were fem ale (49%) and 21 were m ale (51%).  The gender distribution for the  
town as a whole closely follows the expected  distribution when com pared to that of  
Massachusetts (Figure 2).  In Massachusetts , 48% of brain and CNS cancer cases were  
diagnosed in females and 52% were diagnosed in  males.  In the United States, the American  
Cancer Society (ACS) estimates that 17,000 individuals will be diagnosed with brain and/or  
CNS cancers in 2002 with 44% of the diagnoses among fem ales and 56% among males  
(ACS, 2002a).  

When evaluated by smaller time periods, the gender distribution of individuals diagnosed  
with brain and/or CNS cancers in Needham  closely follows that in Massachusetts.  For the  
time period 1987-1993, 47% of the brain and CN S cancer cases in Needham occurred among  
females and 53% occurred among m ales whereas 45% brain and CNS cancer cases in  
Massachusetts occurred among females and 55% occurred am ong males (Figure 3).  For the  
time period 1994-1998, female and male brain and CNS cancer cases in Needham  were 48%  
and 52% while in Massachusetts they were 44% and 56%, respectively (Figure 4).  

However, as noted previously, fem ales in  CT 4033 experienced a statistically significant  
elevation in the incidence of brain and  CNS cancer during the overall time period 1987-1998  
due to a statistically significant elevation during the most recent time period (i.e., 1994- 
1998).  In this census tract during 1987-1998, 57%  of the diagnoses were among females  
while 43% were among males.  During 1994-1998,  60% of the diagnoses in CT 4033 were  
among females while 40% were among males.  

The incidence rates for brain and CNS cancer were calculated and adjusted by age according 
to six age categories: 0-19, 20-44, 45-64, 65-74,  75-84, 85+.  A review of age-group specific  
SIRs for each census tract was not possible because of the small number of diagnoses in each  
group.  However, the age distribution of brain and CNS cancers in Needham  was reviewed.  
In Needham as a whole during 1987-1998, the average age of diagnosis was 45 years.  Four  
individuals were diagnosed between the ages of  0 and 19 (average age = 12.8).  In general,  
the observed distribution of cases by age show ed that the highest percentage of cases  
occurred in individuals who were between 45 and 64 years of age for both Needham  (39%)  
and Massachusetts (30%) (Figure 5).  

C. Race  

In general, brain and CNS cancers occur m ore  frequently in whites than in other races  
(Preston-Martin & Mack 1996).  According to the 2000 U.S. Census, approximately 95% of  
Needham residents are white (U.S. Department of Commerce, 2000).  Additionally, 88% of  
individuals diagnosed with brain and/or  CNS cancers from  1994 to 1998 in Needham  were  
white.  The remaining 12% of individuals were either black or of an unknown race.  

D. Occupation  

Available occupational data for the 41 individuals diagnosed with brain or CNS cancer  
during 1987-1998 was evaluated with respect to suspected risk factors for these cancer types.  
Although studies are not conclusive, occupations  such as plastics manufacturing, aspartame  
(sugar substitute) manufacturing, electrical and electric utility work, verterinarians,  
agricultural work, certain health professions  (e.g., pathologists, physicians, dentists, and  
nurses), nuclear industry work, and rubber industry work m ay be associated with an  
increased risk of developing brain or  CNS cancer (ACS 2002b, Kheifets 2001, Yeni- 
Komshian & Holly 2000, Preston-Martin & Mack 1996).  

Townwide, four individuals reported working  in the health care industry in occupations  
possibly associated with a higher incidence of brain or CNS cancer (e.g., nursing and  
dentistry), however, specific exposures associated with these occupations have not been  
established.  These individuals resided in different areas of town and were not geographically  
concentrated in any one neighborhood or census tract.  Eleven individuals in Needham  were  
reported as retired or with unknown occupations.  The remaining 26 individuals reported  
occupations that are not thought to be associated with an increased risk of brain or CNS  
cancer.  However, from  the available information, it was not possible to assess individual  
occupational exposure to established or suspect ed risk factors for brain or CNS cancer.  
Therefore, although the information reviewed  suggests the possibility that occupational  
exposures m ay have contributed to the development of brain or CNS cancer among some  
individuals, it is difficult to determine what role, if any, occupational exposures played in the  
incidence of brain and CNS cancer in Needham overall.

VII. GEOGRAPHIC  DISTRIBUTION  

Place of residence at the time of diagnosis was mapped for each individual diagnosed with  
brain or CNS cancer in Needham  during the 1987-1998 period to assess any possible  
geographic pattern of diagnoses.  In addition to quantitatively determining census tract- 
specific incidence ratios when possible, a qualitative evaluation was conducted to determine whether brain and CNS cancer cases appeared to be concentrated in some areas within the  
town or within a particular CT.  Because of confidentiality reasons, maps of the locations of  
individuals diagnosed with brain and CNS cancer in Needham  cannot be provided in this  
report.  However, the point pattern of diagnoses was reviewed and the results are summarized  
here.  

During the 1987-1993 period, 16 individuals were  diagnosed with brain or CNS cancer in  
Needham.  No statistically significant elevations were noted in Needham  or any of its CTs  
during this time period.  Additionally, individuals diagnosed with brain or CNS cancer from  
1987 to 1993 lived in locations uniformly distributed throughout the town and, thus, were not  
concentrated in any one area.  

Twenty-five individuals were diagnosed with  brain or CNS cancer  in Needham during the  
1994-1998 time period where approximately 11 diagnoses were expected.  As described  
above, the statistically significant elevation observed townwide was primarily due to  
statistically significant elevations in brain and CNS cancer incidence among residents of CTs  
4033 and 4035 during 1994-1998.  In CT 4033, a geographic concentration of diagnoses was  
noted near the Needham  Junction neighborhood.  Specifically, eight of the ten individuals  
diagnosed with brain and CNS cancer in this CT during this time period resided to the  
northeast of the Needham  Junction Com muter Rail Station (see Figure 6).  Review of case  
information from  the MCR for these individuals revealed that brain and CNS cancer  
diagnoses in this area were distributed  evenly among both m ales and fem ales.  Among  
females diagnosed with brain or CNS cancer in  this area, two were under the age of 19 and  
two were adults of older ages.  Among males diagnosed with brain or CNS cancers in this  
area, ages ranged from  the late 40s to late 70s.  As described above, the incidence of brain  
cancer among both m ales and fem ales peaks during childhood and then, after age 25, risk  
increases with age.  All of the individuals  that were under age 40 at the time of diagnosis  
were diagnosed with astrocytoma, a type of brain cancer most common in younger  
individuals (Preston-Martin & Mack 1996).  Of the five older (over age 40) individuals  
diagnosed in this area, four were diagnosed with glioblastomas or astrocytomas.  These brain  
cancer histologies are the most common for older adults (Preston-Martin & Mack 1996).  

Needham Junction is a high-density residential area and the most densely populated area of  
CT 4033.  The geographic distribution of brain and CNS cancer diagnoses in this census tract  
can likely be attributed at least in part to the increased population density in this area.  The  
role that other factors (e.g., heredity, diet, etc.) m ay have played in brain and CNS cancer  
incidence observed in CT 4033 during 1994-1998 is unclear.  

A statistically significant elevation among both males and females combined was also noted  
in CT 4035 during 1994-1998.  Most of the seven individuals resided in the greater Needham  
Heights area, to the north and northeast of the Needham Heights Commuter Rail Station (see  
Figure 6).  The distribution of cases in the Needham Heights area closely matches the pattern  
of housing density in CT 4035.  Additionally, brain and CNS cancer diagnoses in this area  
were distributed evenly among males and fem ales.  Further, the demographic and histology  
pattern of brain/CNS cancer incidence in this  area was consistent with what would be  
expected based on available medical literature  (i.e., individuals were diagnosed with the  
types of brain and CNS cancers most common for their age groups).  Again, Needham  
Heights is a densely populated area of the town  and no specific pattern of diagnoses with  
respect to place of residence at time of diagnosis emerged when this information was  
reviewed.  

Individuals diagnosed with brain or CNS cancer  in the remaining four CTs for this time  
period were fairly evenly distributed across these areas and were not concentrated in any one 
neighborhood in Needham.

VIII.  AVAILABLE ENVIRONMENTAL IN FORMATION AND CANCER INCIDENCE  

As noted above, several environmental exposures  have been suggested to be related to the  
development of brain and CNS cancer among some individuals.  For example, some studies  
have reported a link between exposure to petroleum-related com pounds, vinyl chloride,  
aspartame, lead, and pesticides and brain  and CNS cancer risk among workers in certain  
industries (ACS, 2002b; Sathiakumar et. al., 2001;  Delzell et. al., 1999; Coccoet al., 1998).  
Although no specific environmental issues were  cited by the Needham  Board of Health as potentially playing a role in the incidence of  brain and CNS cancer in the town, the CAP  
evaluated the locations of potential environmental sources in Needham  in relation to the  
location of individuals diagnosed with brain  and CNS cancer to determine whether a pattern  
of diagnoses exists in relation to these sites.  This included a review of petroleum -related  
and/or hazardous waste sites and spills reported to the MDEP from 1982 to 1993.  Also, brain  
cancer is often described as having a lengthy latency (or development) period, sometimes in  
excess of 20 years, between exposure to a potentially harmful substance and the development  
of the cancer (Preston-Martin & Mack 1996).  Thus, in order to focus on past exposures  
consistent with the latency period often associated with brain/CNS cancers, the sites reported  
to the MDEP during 1982-1993 were comprehensively reviewed.  Environmental spills that  
occurred after this tim e period are unlikely to result in exposures relating to brain and/or  
CNS cancer incidence during the 1987-1998 period.  

Although the Massachusetts General Laws require  that MDEP be notified of contamination  
that exceeds specified levels, it is important to note that chemical concentrations detected in  
environmental media do not necessarily represent a health threat.  In order for a compound to  
impact one’s health, it must not only be present in a certain environmental media but one  
must also com e into contact with the com pound via the contaminated media (e.g., through  
ingestion, inhalation, or skin absorption).  Therefore, the presence of contaminants at a site  
alone does not necessarily indicate a potential health impact to nearby residents.  However,  
the pattern of individuals diagnosed with brain and CNS cancers in Needham in proximity to  
the site m ay indicate that an environmental factor could be related to the incidence of this  
cancer type in Needham.  

A summary of the spills in Needham  reported  to MDEP from  1982 to 1993 is presented in  
Table 4.  A total of 176 hazardous waste sites, confirm ed spills, or potential spills were  
reported to MDEP from  1982 to 1993.  Approximately 26% of sites reported to MDEP  
during this time period did not have sufficient  address information to allow for mapping of  
the site location.  The locations of the sites with sufficient address information (about 130  
sites) are shown in Figure 7.  Of all the reported sites, the type of material found at a  
particular site was unknown for 11%.  Seventy-nine percent of waste sites in Needham during this time period involved petroleum-related chemicals (e.g., oils, fuels, gasoline).  The  
remaining 10% of sites involved other  chemicals (e.g., metals, organic com pounds,  
pesticides).  The locations of these sites were  evaluated in relation to the places of residence  
of individuals diagnosed with brain or CNS cancer in Needham from 1987-1998.  

Although some scientific studies have found that long-term  occupational exposure to high  
levels of petroleum -related chemicals m ay lead to the development of brain cancer  
(Sathiakumaret. al., 2001; Delzell et. al., 1999), no studies are currently available that  
evaluate any possible associations between  lower-level environmental exposures (i.e.,  
exposures that might occur in a residential setting) to petroleum-related chemicals and brain  
cancer.  Specific details regarding the source and quantity of spills was not available f or the  
majority of sites.  However, many of these releases occurred at gas stations or involved leaks  
from underground storage tanks or vehicle fuel  tanks.  Based on a review of the available  
information, it is unlikely that residents of Needham would have been exposed to significant  
levels of petroleum -related compounds associated with reported spills.  Further, no specific  
spatial pattern of diagnoses in CT 4033 or 4035 (w here statistically significant elevations of  
brain and CNS cancer were noted during 1994-1998) , or in any other area of the town, was  
observed in relation to the locations of these sites.  

Some studies have indicated that occupational exposure to vinyl chloride, lead, aspartame, or  
pesticides may contribute to the development of brain cancer.  Three waste sites reported to  
MDEP between 1982-1993 were described as involving one of these chemicals.  Two of  
these sites were not located in any areas of  town proximal to places of residence for  
individuals diagnosed with brain or CNS cancer between 1987 and 1998.  One of these sites,  
reported to MDEP in 1983, involved polyvinyl chloride (PVC) and was located on Junction  
Street in the Needham  Junction area of CT  4033, where several cases of brain and CNS  
cancer were noted in the 1994-1998 period.  The amount of PVC associated with this site is  
unknown.  Although some scientific studies to date have suggested a possible association  
between occupational exposure to vinyl chloride, a colorless gas used in the manufacturing of  
PVC and plastics, and the development of brain and other cancers (McLaughlin & Lipworth,  
1999), exposure to PVC, an inert solid, has  not been linked to brain and CNS cancer. Moreover, there is no evidence that residents of  the Needham Junction area were exposed to  
contamination associated with this site.  

Thirty-three percent of the sites listed with MDEP during the 1982-1993 time period were  
located in CT 4035. A statistically significant elevation among both m ales and fem ales  
combined was also noted in CT 4035 during the 1994-1998 period.  Generally, many of the  
waste sites in this CT were located east of Interstate 95 in an industrial area.  Although this  
region is primarily industrial, a small residential neighborhood is located within this area.  
However, no spills were reported from  1982-1993 in this residential community.  
Additionally, no cases of brain or CNS cancer were reported in this neighborhood from 
1987-1998.  

Nineteen waste sites were reported to MDEP  as being located in CT 4033 from  1982-1993.  
This comprises about 11% of all waste sites reported in Needham for this time period.  In CT  
4033, a statistically significant elevation of brain and CNS cancer was noted during the 1994- 
1998 time period.  However, review of the geographic distribution of individuals diagnosed  
with brain or CNS cancer in this CT in relation to the locations of reported waste sites did not 
suggest a spatial correlation.

IX.  DISCUSSION  

Despite a statistically significantly lower-than- expected rate of brain and CNS cancer in  
Needham during 1987-1993, statistically significant  elevations in the incidence of these  
cancers were noted in the town as a whole and for Needham  CTs 4033 and 4035 during the  
1994-1998 time period.  A geographic concentration of several individuals who were  
diagnosed with brain and/or CNS cancers  in CT 4033 during 1994-1998 was noted near the  
Needham Junction area.  It is important to note that this area is a more densely populated area  
of town.  Most of the individuals diagnosed with brain and/or CNS cancers during 1994-1998  
who lived in this area had disease characteristics (e.g., gender, age at diagnosis, and histology  
type) that are consistent with what would be  expected based on established patterns of brain  
and CNS cancer.  Finally, the environmental data reviewed did not suggest that residents of Needham diagnosed with brain and/or CNS cancer  were likely to be at risk of exposure to a  
common environmental contaminant associated with hazardous waste sites in the town.  

Although several individuals diagnosed with  brain and/or CNS cancer during 1994-1998 in  
Needham lived in the greater Needham  Heights area in CT 4035, the disease characteristics  
and traits (e.g., age, histology, gender, race) noted  in these individuals was also consistent  
with what would be expected based on the current scientific/medical literature.  Additionally,  
the distribution pattern of individuals diagnosed with brain or CNS cancer during this time  
period was consistent with the pattern of  housing density in this area and no specific  
concentration of diagnoses was noted in relation to any waste sites reported to MDEP.  Thus,  
the elevation of brain/CNS cancer incidence in CT 4035 during 1994-1998 does not appear to  
be due to any particular environmental exposure or factor.  

Other than the elevation observed during 1994-1998,  the pattern of brain and CNS cancer in  
Needham occurred as expected with regard to  age, gender, and histology.  Despite numerous  
scientific and medical investigations, the causes of brain and CNS cancer remain largely  
unknown.  Among the possible risk factors investigated  in relation to this type of cancer are  
ionizing radiation, electromagnetic fields, occupational exposures (as discussed above),  
exposure to nitrites and other N-nitroso compounds, head trauma, and genetic disorders.  Of  
these, the most established risk factor is high-dose exposure to ionizing radiation (i.e., x-rays  
or gamma rays) (ACS, 2002b).  There is no obvious source of ionizing radiation in Needham.  
Moreover, there is no historical evidence of high levels of nitrites/nitrates (or any other 
contaminant) in the Needham  drinking water supply (Needham  DPW , 2002).  For m ore  
information on risk factors associated with  brain and CNS cancer, please refer to Appendix A.

X. CONCLUSIONS  

Although statistically significant elevations in  the incidence of brain and CNS cancer were  
observed in Needham  CTs 4033 and 4035 during 1994-1998, review of the available case  
information, environmental data, and geographic pattern of diagnoses does not suggest a  
common factor (environmental or non-environmental) related to these diagnoses.  For some  
individuals, it is possible that occupational exposures could have played a role.  It is unknown whether individual risk f actors (i.e., exposure to ionizing radiation, genetics, head  
injury, etc.) or the role of chance may also be related to some of these diagnoses.  

A review of recent data from  the MCR suggest s that the elevation in brain and CNS cancer  
incidence observed in Needham  during 1994-1998  may not be persisting over time.  Seven  
diagnoses of brain and CNS cancer in Needham have been reported to the MCR since 1999.  
Although standardized incidence ratios cannot  be calculated due to incomplete cancer  
incidence data for the state, this number appears to be consistent with the expected number of  
diagnoses based on the population of the town.  Moreover, the individuals diagnosed with  
brain and CNS cancer are not concentrated  in CT 4033, CT 4035, or any other part of  
Needham but are distributed fairly evenly throughout the town.

XI.  RECOMMENDATIONS  

The Community Assessment Program recommends no further investigation at this time based  
on the information reviewed.  However, we will  continue to monitor the incidence of  brain  
and CNS cancers in Needham through the Massachusetts Cancer Registry to determine if the  
patterns of these cancers change.  

REFERENCES  

American Cancer Society.  2002a.  What are the key statistics for brain and spinal cord tumors?  
Available: 
http://www.cancer.org/eprise/main/docroot/CRI/content/CRI_2_4_1X_What_are_the_key_statist  
ics_for_brain_and_spinal_cord_tumors_4?sitearea=CRI  [cited 03-Sept-2002].  

American Cancer Society.  2002b.  What are the risk factors for brain and spinal cord tumors?  
Available: 
http://www.cancer.org/eprise/main/docroot/CRI/content/CRI_2_4_2X_What_are_the_risk_facto  
rs_for_brain_and_spinal_cord_tumors_3?sitearea=CRI  [cited 03-Sept-2002].  

Cocco P, Dosemeci M, and Heineman EF. 1998. Brain cancer and occupational exposure to lead.  
J Occup Environ Med 40(11):937-42.  

Delzell E, Beall C, Rodu B, Lees PS, Breysse PN , and Cole P.  1999.  Case-series investigation  
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Environmental Systems Research Institute (ESRI) 2002.  ArcGIS,  Arcview  license,  ver.  8.2,  
Redlands, California.  

Kheifets LI. 2001. Electric and magnetic field exposure and brain cancer: a review.  
Bioelectromagnetics Suppl 5: S120-S131.  

Massachusetts Department of Environmental Protection (MDEP).  2002.  Downloadable waste  
sites databases.  Available:  http://www.state.ma.us/dep/bwsc/sitelist.htm  [cited 05-Sept-2002].  

Massachusetts Department of Public Health (MDPH).  2001.  Cancer Incidence in  
Massachusetts 1994-1998, City and Town Supplement.  Massachusetts Department of Public  
Health, Bureau of Health Statistics, Research  and Evaluation, Massachusetts Cancer Registry,  
Boston, MA.  

McLaughlin JK, and Lipworth L.  1999.  A critical  review of the epidemiologic literature on  
health effects of occupational exposure to vinyl chloride.  J Epidemiol Biostat 4(4): 253-275.  

Needham Department of Public Works. 2002. Personal communication with Bill Wanberg,  
Water Treatment Manager, Needham Department of Public Works.  November 25, 2002.  

Preston-Martin S, Mack W . 1996. Neoplasm s of the nervous system . In: Cancer  
Epidemiology and Prevention. 2nd Ed, edited by Schottenfeld D,  Fraumeni. JF. New York:  
Oxford Press University: 1996.  

Rothman KJ, and Boice JD. 1982.  Epidemiologic Analysis with a Programmable Calculator.  
Boston: Epidemiology Resources, Inc.  

Sathiakumar N, Delzell E, Rodu B, Beall C, and Myers S.  2001.  Cancer incidence among  
employees at a petrochemical research facility. J Occup Environ Med 43(2): 166-174.  

U.S. Department of Commerce, Bureau of  the Census, 1990, Census of Population and  
Housing.  

U.S. Department of Commerce, Bureau of the Census, 2000, Census of Population and  
Housing.  

Yeni-Komshian H, Holly EA. 2000. Childhood brain tumours and exposure to animals and farm  
life: a review. Paediatr Perinat Epidemiol  14(3): 248-256.  

APPENDIX A:   
Risk Factor Information for Brain and CNS Cancer

Extracted pictures

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