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MA EPHT - Cancer

Cancer is not one disease but a group of diseases that may be caused by several factors acting together over time. The Massachusetts Environmental Public Health Tracking (MA EPHT) program provides direct incidence rates and standardized incidence ratios for many types of cancer diagnosed among Massachusetts residents.

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Explore cancer data 

What is cancer?

Cancer is a term used to describe a variety of diseases associated with abnormal cell and tissue growth. There are more than 100 different types of cancer, each with separate causes, risk factors, characteristics, and patterns of survival. 

A risk factor is anything that affects a person's chance of developing cancer. They may include inherited conditions, medical conditions or treatments, lifestyle factors, or environmental exposures. An individual’s risk of developing cancer may depend on several risk factors that act together and can change over time. 

Cancers are classified by the location in the body where the disease originated (the primary site) and the tissue or cell type (histology). Cancers that occur as the result of metastasis (or spread) of a cancer to another location in the body are not considered separate cancers.

In general, most cancers have a long period of development (also known as a latency period) thought to range from 10 to over 50 years. While not much is known about the latency period for cancers that occur in children, it is assumed to be considerably shorter than in adults.  

The social, physical, and built environments in which people live impact their quality of life. They may be exposed to things in their environment that cause cancer.

How does MA EPHT track cancer incidence?

MA EPHT collaborates with the Massachusetts Cancer Registry (MACR) to present data on the incidence (new diagnoses) of cancer among Massachusetts residents in tables, graphs, and maps. The MACR is a population-based cancer registry established in 1980. All health care facilities in Massachusetts are required by law to report diagnoses of cancer to the registry. This includes diagnoses of malignant disease and benign brain-related tumors.

Each year, the North American Association of Central Cancer Registries (NAACCR) reviews cancer registry data for quality, completeness, and timeliness. For each year during 2000-2018 and 2020, NAACCR estimated the MACR’s annual case count to be more than 95% complete, reaching the gold standard. The estimate for 2019 was more than 90% complete, receiving a silver certification. 

Why does cancer seem to occur more often in certain places?

Cancer is common. According to the American Cancer Society, one in three women and one in two men will develop cancer during their lifetime. For this reason, cancers often appear to occur in “clusters,” and it is understandable that someone may feel that the number of cancer diagnoses in their neighborhood or town is unusual. Upon close examination, many of these “clusters” are not unusual as first thought, but are due to population density, shared behaviors or risk factors, or random chance. Sometimes higher rates are due to improved diagnostic techniques and changes in data collection. Yet, others are unusual; that is, they represent a true excess of cancer in a community, workplace, or other subgroup of people. A suspected cluster is more likely to warrant further investigation if it involves: 

  • Many diagnoses of one type of cancer
  • Diagnoses of a rare cancer type
  • Diagnoses among individuals in age groups not usually affected by that cancer type

The U.S. Centers for Disease Control and Prevention (CDC) defines a cancer cluster as a greater than expected number of cancer diagnoses that occurs within a group of people in a geographic area over a period of time. A person may suspect that a cancer cluster exists when several loved ones, neighbors, or coworkers are diagnosed with cancer.  However, what appears to be a cluster may actually reflect the expected number of cancer diagnoses within the group or area. 

How are patterns of cancer evaluated?

DPH's Bureau of Climate and Environmental Health (BCEH) uses a phased approach for community-specific environmental health assessments. This approach aligns with CDC’s Guidelines for Examining Unusual Patterns of Cancer and Environmental Concerns published in 2022. 

DPH looks at the number of diagnoses of a specific cancer type that occur over a certain time in a city, town, or census tract. This number is compared to the number that would be expected based on the statewide experience. The difference between the observed and expected numbers of diagnoses may be statistically meaningful or due to random chance. For screening-level reviews, analysts assess this data over time to look for trends. They also look at:

  • Age at diagnosis
  • Specific cancer cell type (called histology)
  • Relevant risk factors
  • Spatial pattern of diagnoses compared to population density, distance to a potential source of exposure, or other features

Taken together, this information indicates whether an unusual pattern of cancer exists. In some cases, the findings may warrant additional public health investigation.

Cancer incidence evaluations previously conducted by the DPH Bureau of Climate and Environmental Health are available for many regions and communities in Massachusetts.

For more information on challenges and limitations of investigating patterns of cancer, see CDC’s fact sheet.  

What is known about cancer and the environment?

Many cancers occur because of changes to cells that happen by random chance. These are called sporadic or spontaneous mutations. These mutations are not due to any particular exposure to a cancer-causing agent. Other times, exposure to cancer-causing agents (called carcinogens) may be a contributing factor.

If a person is exposed to something, it does not necessarily mean that their health will be affected. The risk of harm from exposure to a carcinogen depends on several factors. This includes the type, extent, and duration of exposure. For example, breathing a certain chemical may increase your risk of getting cancer but touching the same chemical may not. Some substances may increase risk only if the levels are high and exposure occurs over a long time.

The relationship between exposure and the development of cancer is complex. It is not possible to predict if a specific environmental exposure will cause an individual person to develop cancer. This also means that we usually don't know why one person gets cancer and another does not.

Available data

Use the Explore cancer data link on this page to access the following measures for cancer:

  • Average annual case count and direct age-adjusted incidence rate per 100,000 by county and statewide
  • Observed number of diagnoses, expected number of diagnoses, and Standardized Incidence Ratio (SIR) by census tract, city/town, EP region, or EOHHS region

The most current available data will be shown. Be sure to check the site periodically as new data is added. To protect privacy, no information is shown that could potentially identify an individual.

Cancer data are presented on the MA EPHT website using two different types of statistics:

Direct age-adjusted incidence rates

  • A direct age-adjusted incidence rate is the most appropriate statistic to compare cancer incidence in one relatively large area like a county or state to another
  • Direct rates are age-adjusted because cancers do not impact different age groups equally. Rates are calculated by applying age-specific cancer rates in an area to the U.S. standard population.
  • Direct rates are available for 15 types of cancer and two subtypes of leukemia (acute myeloid leukemia and chronic lymphocytic leukemia) for individuals of all ages
  • Direct rates are available for two childhood age groups (0-15 and 0-19 years of age) for cancers of the brain and central nervous system, leukemia, and two leukemia subtypes (acute lymphoid leukemia and acute myeloid leukemia)  

Standardized incidence ratios (SIRs)

  • A Standardized Incidence Ratio (SIR) is the most appropriate statistic to examine cancer incidence in a small area, such as a city/town or a census tract
  • An SIR is the ratio of the observed number of cancer diagnoses to the number of expected diagnoses multiplied by 100
  • The observed value is the number of new diagnoses of a particular cancer type that occurred among residents of an area during a given 5-year period
  • The expected number of diagnoses reflects the number of diagnoses anticipated to occur among residents of an area during a 5-year period based on the statewide experience. It is calculated by applying the age and sex-specific statewide incidence rates to the population distribution of the community or census tract.
  • SIRs for different areas cannot and should not be compared to each other. Rather, the SIR indicates whether the cancer incidence of an area differs from that of the state as a whole.
  • SIRs are available for 24 different types of cancer and all cancers combined, which is a measure of the overall cancer burden
  • For more information on SIRs, see CDC’s fact sheet 

Related links

Massachusetts Cancer Registry (MACR)  MACR city and town cancer dashboard  Cancer risk factor summaries   DPH/BCEH cancer in Massachusetts information sheet  DPH/BCEH environmental health investigations   Massachusetts Comprehensive Cancer Coalition  DPH Comprehensive Cancer Control Program  DPH Breast and Cervical Cancer Program  DPH Colorectal Cancer Control Program 

Additional resources

Massachusetts

National

Contact

Online

MA EPHT Website 
Email Massachusetts Environmental Public Health Tracking (MA EPHT) at DPH-MA-EPHT@state.ma.us

Phone

Call Massachusetts Environmental Public Health Tracking (MA EPHT) at (617) 624-5757

Address

250 Washington Street, Boston, MA 02108
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