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Community cancer investigations

The Colorado Central Cancer Registry responds to concerns about possible cancer clusters thought to be related to environmental risks.

  • A cancer cluster is a greater-than-expected number of cancer cases that occur within a group of people in a geographic area over a specific period. We use CDC guidelines to determine whether an excess number of cancers have occurred.
    • When a suspected cancer cluster has been identified, we investigate whether the cancer cases can be linked to an environmental exposure.
  • Data routinely collected by the cancer registry provide an important tool to respond to community and occupational concerns.
  • All cancers diagnosed in Colorado are reported to the registry with the exception of non-melanoma skin cancers.

Understanding cancer

Cancer is not a single disease but a group of more than 100 different diseases that share some common characteristics. Cancer is the second leading cause of death in Colorado and the United States. One out of every three people is expected to be diagnosed with cancer in their lifetime. 

The most common risk factors are: 

  • Growing older
  • Tobacco
  • Excessive exposure to the sun
  • Ionizing radiation
  • Certain chemicals and other substances
  • Some viruses and bacteria
  • Certain hormones
  • Family history of cancer
  • Alcohol
  • Unhealthy diet, lack of physical activity, or obesity

Overall, a relatively small number of cancers are linked to toxic substances in the environment or workplace. Even when we know a substance can cause cancer, the risk of developing it depends on how much of the substance a person was exposed to and for how long.

How do you investigate cancers in a community?

When there is concern about cancer in a community, CDPHE works with local agencies to gather the information we need to investigate. This information includes details about the geographic area, possible environmental exposures, and specific cancer types.

We combine this information with Colorado Central Cancer Registry data. Hospitals, health care providers, and laboratories report cancer cases to the registry. These data enable us to determine how the number of cancer cases in the community compares to the average number expected based on Colorado cancer incidence rates.

What is the Colorado Central Cancer Registry (CCCR)?

The Colorado Central Cancer Registry analyzes cancer data. This data helps us answer important questions about cancer incidence, prevention, and treatment. Colorado state law and Board of Health rules require hospitals, clinics, health care providers, and laboratories to report this information to the Registry. The Registry collects data on all cases of cancer except non-melanoma skin cancer.

What is a cancer cluster?

Many cases of cancer occurring near each other are sometimes referred to as a “cluster.” People may report that several family members, friends, neighbors, or co-workers have been diagnosed with cancer.

When we investigate, we find most reported clusters are coincidences. There are usually different kinds of cancer in the group, and the number of cases is typically close to what is expected. But sometimes, a cluster is related to public health factors that may place people at greater risk. These reports warrant further investigation.

What information do you require for a cancer investigation?

Case confirmation: We must confirm each reported cancer case in the community. We review medical information to gather details about the cancer case.

Type of cancer: Since cancer is many different diseases, we cannot analyze all types of cancer together as one group. Different kinds of cancer occur at different rates. So, it is important to consider the number of each type of cancer.

Study population: We define the study population by geographic boundaries, such as ZIP codes, or U.S. Census areas, such as, census tracts or block groups. By using geographic boundaries, we can get age, sex, and race/ethnicity population counts.

What happens when a cancer cluster is reported?

There are three possible outcomes:

  1. The numbers and types of cancer in the study population are the same or similar to the expected numbers and types based on Colorado statewide cancer incidence. This means no community-specific risk factor could be identified.
  2. While some numbers and types of cancer in the study population are higher than expected based on Colorado statewide cancer incidence, there are clear differences in common cancer risk factors between the study population and the state as a whole. For example, the study population with more cancer cases also has higher rates of tobacco use or HPV than those rates for Colorado as a whole. This means the department cannot determine whether the elevated numbers of cancer are due to a community-specific risk factor (such as an environmental exposure) or to the other common cancer risk factors.
  3. The numbers and types of cancer in the study population are higher than expected based on Colorado statewide cancer incidence. There are no clear differences in common cancer risk factors between the study population and Colorado as a whole. This means a community-specific risk factor may be responsible for the higher than expected cancer cases, and agencies need to take action to identify the source (if possible) and reduce exposure.
     

What happens if cancer incidence is elevated in a community?

The department’s mission is to advance Colorado’s health and protect the places where we live, learn, work, and play. When a community has higher than expected rates of cancer with no clear differences in the common cancer risk factors, the department will collaborate with local, state, and federal partners to identify the source (if possible) and reduce exposure.

Where should I report a suspected community cancer cluster?

Report suspected clusters to the Colorado Central Cancer Registry. CCCR staff review medical records for each cancer patient to confirm the accuracy and completeness of the reports. We keep all patient, physician, and hospital information private and confidential, as required by state law.

Colorado Central Cancer Registry
303-692-2540
cdphe.pscaregistry@state.co.us

What can I do to reduce my risk of getting cancer?

Cancer is common. One out of every three people is expected to be diagnosed with cancer in their lifetime. Even people who "do all the right things" sometimes still get cancer.

Prevention and early detection is key. You can take steps now that could greatly reduce your risk of getting cancer. 

  • Talk to your health care provider about appropriate screenings based on your family history, lifestyle, and potential environmental exposures. 
  • Avoid tobacco use
  • Drink less alcohol
  • Wear sunscreen
  • Get enough exercise