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December 12, 2017
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community living

Community cancer rates

By James D. Lomax, MD

A cancer cluster is defined by the Center for Disease Control (CDC) as “a greater than expected number of cancer diagnoses in general; larger number of a particular kind of cancer within the area; and a larger number of a cancer diagnoses within a given population of people living in that area (e.g., race, ethnicity, age group or gender, etc.)” One occasionally hears about suspected clusters in our own area.

Abundant statistics are available online about cancer rates by county and state, e.g. for PA or for New York. However, interpreting this information and identifying possible environmental cause(s) is very complex and potentially misleading. Cancers are common, and cases may appear to occur at an alarming rate within a community even if the number of cases is within the expected rate for that size population. The specific geographic area and time period studied are also important parameters.

Identifying a potential problem

It is often a local health care professional or community member who begins to notice an increase in the diagnosis of a particular kind of cancer in a family, community, workplace, or school. Usually the state department of health is contacted, which sets offs a protocol to investigate the report. The public health official should respond quickly to the contact’s concerns, gather the necessary demographic information about the affected individuals, determine if the incidence of that kind of cancer exceeds expected levels in that area and then launch a full investigation if so.

Risk factors for developing cancer

There are more than 100 different kinds of cancer. Cancer represents the breakdown of the normal orderly process of new cell growth. Body cells die and are replaced with new cells in most body tissues. Tumors develop when new cells continue to grow when this is not needed. If the DNA of a cell is damaged or abnormal, the uninhibited growth of those cells will ultimately form tumors—either benign or metastatic disease. At present, researchers have identified over 300 specific genes that have shown alterations or damage and were associated with the growth of tumors.

What causes cancer can be broken down to internal (within the person) and external exposure from the environment. Internal factors include cancers that run within a family. Examples of genetic/internal factors would be breast cancer that runs in closely related women in a family, or colon cancer related to multiple polyps. It does not mean, however, that everyone in that family will develop a tumor, but that they are at higher risk and need to screened more frequently, starting at a younger age.

External exposure to cancer-causing agents includes exposure at home, work, or in the environment in general (air, contaminated soil, or radiation exposure). Other important factors to note with regard to external exposure are that there is often a 10- to 15-year lag between the exposure and the development of disease, along with effects of aging, smoking, excessive alcohol intake, inactivity, obesity and other personal high-risk behaviors.

A special mention concerning exposure to electromagnetic fields (EMFs) and the development of cancer is important. We are constantly exposed to many different types of electric and magnetic fields. There are high frequency sources such as X-ray and external gamma rays (from outer space) or exposure to high voltage powerlines that potentially can cause DNA damage. Lower frequency sources include radio, television signals, microwave ovens, cell phones and other household appliances.

There is controversy as to whether these exposures do lead to cancer, especially in children. Many retrospective studies have been performed to see what type of EMF and frequency of exposure are associated with cancer. To date there has been no strong association found in developing cancer when looking at previously published data. Again, there is the issue of the lag period of exposure to development of tumors—sometimes years. The Internet lists many contrary views that disagree with these studies. It will take many carefully controlled, long-term studies of exposure to EMFs to resolve this issue.

Examples of workplace and community exposures that potentially increase cancer risk
• Unprotected exposure to pesticides in agricultural workers associated with blood, lymphomas, stomach, brain and prostate cancer
• Increased risk of healthcare personnel with exposure to chemotherapy agents associated with developing lymphomas
• Unprotected industrial exposure to solvents, benzene, fibers, fine particles and dust, dioxins and heavy metals associated with multiple kinds of cancers
• Exposure to contaminated fill dirt, especially cadmium, leading to lung cancer
• Radon exposure in basements of homes and buildings or from radiation leakage from reactors into the environment