- Investigation of Hodgkin's Disease Among Former Methuen High School Students, July 2003 file size 4MB
Questions and Answers
1. Why was a study of Hodgkin's disease conducted in Methuen?
In 1995 a Methuen resident contacted local health officials in Methuen with concerns about a possibly unusual number of former students or graduates of Methuen High School who had been diagnosed with Hodgkin's disease. The Methuen Board of Health then contacted the Massachusetts Department of Public Health, Bureau of Environmental Health Assessment (MDPH/BEHA), for assistance in evaluating these concerns.
2. What was done by the MDPH/BEHA in response to the initial concerns about Hodgkin's disease?
MDPH/BEHA initially evaluated the latest available data at the time from the Massachusetts Cancer Registry (MCR) for Hodgkin's disease among all Methuen residents. That review revealed that the town overall was not experiencing an unusual incidence of Hodgkin's disease during the period 1982-1990, the most recent period available for review at the time. However since a number of Methuen High School graduates had moved from the town, questions still remained. For that reason MDPH recommended a follow-up study.
3. What follow-up study was conducted?
The primary focus of the follow-up investigation was to conduct personal interviews, collect biological samples, (e.g., blood), and analyze the combined information to help learn more about Hodgkin's disease among this group of individuals. In addition, the MDPH estimated an expected number of Hodgkin's disease cases among students or graduates of Methuen High School during the time period of interest to compare with the observed number of cases.
4. Did MDPH/BEHA seek outside assistance to develop a study protocol?
Yes. MDPH/BEHA sought technical assistance from Dr. Nancy Mueller of the Harvard School of Public Health (HSPH), who has conducted extensive research on Hodgkin's disease and is a world-renown expert in the epidemiology of this disease. Dr. Mueller assisted on the development of a study protocol, provided graduate students to assist MDPH in its work, and peer-reviewed the final study report.
5. How was a "case" defined in this study?
Individuals who had attended or graduated from Methuen High School during the years 1979-1993 and whose diagnoses during 1982-1995 were confirmed by MCR were eligible as a "case" for the follow-up investigation.
6. What data were collected in the interviews of the Methuen High School graduates/attendees that participated?
All participants or their next-of-kin were interviewed by MDPH/BEHA staff/interns using a questionnaire that has been used by Dr. Mueller of the Harvard School of Public Health in her research. The questionnaire focused on gathering information on known risk factors for Hodgkin's disease (e.g., number of siblings, maternal education).
7. What other data were collected from the MDPH participants?
All participants were also asked to provide a blood sample and allow previous tissue blocks that were available at a diagnosing or treating hospital to be analyzed for the purpose of determining the presence of specific biomarkers that indicated a history of Epstein-Barr viral (EBV) infection.
8. Why is information on EBV important?
Although EBV infection is extremely common and usually harmless, it is the virus that has been linked most specifically with Hodgkin's disease.
9. How did MDPH determine if the pattern of Hodgkin's disease among former students or graduates of Methuen High School was unusual?
In order to determine whether individuals diagnosed with Hodgkin's disease had unusual characteristics or risk factors relative to a larger comparison group of individuals with Hodgkin's disease, the MDPH participant risk factor profiles were compared to 239 Hodgkin's disease patients in the same age group who were enrolled in a population-based study of Hodgkin's disease in the Greater Boston area that is currently being conducted at the Harvard School of Public Health (HSPH).
10. How many people were identified or potentially eligible for the MDPH interview study?
A total of 14 people were identified as potential participants in the MDPH interview study either through reports to the Department of former students or graduates of Methuen High School who were diagnosed with Hodgkin's disease or through a search of the MCR files. Of these, three individuals could not be located and three individuals either did not attend Methuen High School or were diagnosed with Hodgkin's disease prior to attending the high school. Thus, eight individuals met the case definition for the interview study.
11. How many of the eight individuals who met the case definition for this study agreed to participate in the interview study?
Of eight individuals eligible to participate, seven agreed to participate in the follow-up interview study.
12. What were the ages of the study participants?
All study participants were diagnosed with Hodgkin's disease between the ages of 15 and 39 years old, which is considered the age range for young adult Hodgkin's disease.
13. What did the study find about Hodgkin's disease among former students or graduates of Methuen High School?
Evaluation of interview, serology (i.e., blood serum), and tissue block data indicated that the MDPH participants had Hodgkin's disease risk factor profiles generally similar to the larger comparison group of Hodgkin's disease patients from the Greater Boston area under study by the Harvard School of Public Health.
14. What were some of the risk factors that the scientific literature has shown to be associated with Hodgkin's disease and that were seen in the MDPH participants?
MDPH participants had socioeconomic and childhood environment characteristics that have been shown previously to be risk factors for Hodgkin's disease (e.g., higher socioeconomic status based on single-family and owner-occupied homes, small family size and early birth order; high maternal education). It is interesting to note that the MDPH participants showed somewhat higher socioeconomic indicators than Methuen as a whole during their childhood, suggesting that this group was at somewhat higher risk of Hodgkin's disease than the general Methuen population.
15. Why are factors such as socioeconomic status or childhood environment thought to be associated with Hodgkin's disease?
Socioeconomic and childhood environment characteristics are thought to reflect a greater likelihood of later infection to common childhood viruses, such as the EBV, which in turn is thought to be a risk factor for subsequent development of young adult Hodgkin's disease. For example, children with no or few siblings do not develop immunity as strongly as children with larger numbers of siblings. More recent social behavior changes, such as increasing attendance at nursery schools, which appears to be protective, may currently be reducing the effect of family structure or other childhood environment factors on Hodgkin's disease risk. Attendance at nursery schools, which has increased from about 5 percent in the 1960s to about 50 percent in the 1990s, may increase the likelihood of earlier exposures to common childhood viruses, thereby reducing the risk of subsequent development of Hodgkin's disease. Interestingly, none of the seven MDPH participants reported attending nursery school.
16. What is the possible role of Epstein-Barr virus in Hodgkin's disease?
The association between Epstein-Barr virus (EBV) and Hodgkin's disease is well established. EBV is a herpes virus and has a widespread distribution throughout the world with more than 80 percent of healthy adults infected by the third decade of life. Primary infection is usually asymptomatic but when infection is delayed until adolescence, as is frequent in developed countries, EBV causes infectious mononucleosis in about 50 percent of cases.
17. Why is infectious mononucleosis important as it relates to Hodgkin's disease?
Several studies have shown an association between Hodgkin's disease and a prior diagnosis of infectious mononucleosis. This association appears primarily among young adult patients (all MDPH interview participants were young adults when diagnosed). A recent study found a three-fold increased risk of Hodgkin's disease in young adults with a prior diagnosis of infectious mononucleosis.
18. What did the biological tissue analyses of the MDPH participants show?
The results of blood and tissue block analyses showed a pattern consistent with the literature and also similar to that seen in the HSPH comparison group, again indicating that the MDPH participants were not unusual in terms of what has been measured among a larger group of young adults from the Greater Boston area diagnosed with Hodgkin's disease. The cell type of Hodgkin's disease and indicators of immune responses to the presence of EBV were similar in the MDPH group as the scientific literature indicates for young adults diagnosed with Hodgkin's disease. Two of the MDPH participants also had been previously diagnosed with infectious mononucleosis.
19. Was there an unusual number of Hodgkin's disease cases among Methuen High School students or graduates during 1982-1995?
MDPH estimated an expected number of Hodgkin's disease cases for the cohort of Methuen High School students during the 1982-1995 time period, which corresponded to the period for which statewide incidence data were available for comparison and during which the reported Methuen cases were diagnosed. Given the population data for the high school during 1982-1995 and statewide incidence data for Hodgkin's disease. The expected number of individuals diagnosed with Hodgkin's disease in this cohort was estimated at 3.96, or approximately four. The observed number of individuals who were in this cohort was six. Thus, more cases of Hodgkin's disease occurred among Methuen High School students than expected for the 1982-1995 time period. However, this difference was not statistically significant when compared with the statewide experience.
20. What is the latest information from the Massachusetts Cancer Registry on the incidence of Hodgkin's disease for Methuen as a whole?
Hodgkin's disease occurred about as expected in Methuen as a whole during 1990-1995. During 1995-1999, four individuals were diagnosed with Hodgkin's disease among females versus about three expected. Among males there was a statistically significant elevation during 1995-1999. A detailed review of available information from the MCR for the 1995-1999 time period did not indicate unusual age, temporal, or cell type distributions among males. Furthermore, there did not appear to be any temporal concentration (i.e., more cases in certain years) or geographic clustering within any area of Methuen.
21.What did MDPH conclude from this study?
All of the information reviewed in this investigation suggests that the pattern of Hodgkin's disease seen among this group of former students or graduates of Methuen High school does not appear unusual in terms of risk factor characteristics that have been linked with Hodgkin's disease risk among young adults.
22. Did any factors emerge from the study that suggested Methuen High School played a primary role in Hodgkin's disease among the group?
No. The seven MDPH participants were not remarkably different from the 239 HSPH cases that served as a representative group of young adult Hodgkin's disease patients from the Greater Boston area. No two MDPH interview participants were believed to be members of the same Methuen High School graduating class, with graduation dates varying over the time period 1979-1993. There did not appear to be a temporal pattern with respect to date of diagnosis and attendance at the high school.
23. Have other studies evaluated possible clusters of Hodgkin's disease in high schools or other buildings?
Yes. Dr. Mueller reviewed evidence for clustering or aggregation of exposure of Hodgkin's disease (e.g., among high school populations) that might be attributable to Hodgkin's disease being a contagious disease that could be transmitted by person-to-person contact. However, Dr. Mueller concluded that while a viral etiology remains suspect, on balance there is little to support hypotheses suggesting that such viruses present contagious disease concerns.
24. Does MDPH plan to conduct more studies in Methuen?
Information reviewed in this report did not indicate that attending Methuen High School is likely to play a primary role in the pattern of Hodgkin's disease occurrence among former students or graduates of the high school. Thus, MDPH/BEHA does not recommend further evaluation of Hodgkin's disease among Methuen High School students or graduates at this time. MDPH/BEHA will continue to monitor Hodgkin's disease incidence in Methuen through the Massachusetts Cancer Registry.
25. Where can I obtain a copy of the report?
A copy of the report will be available on the MDPH/BEHA website at www.state.ma.us/dph/beha
26.Who should I contact for more information?
You can contact BEHA at 617-624-5757.