A cancer "hot spot" is a region with an unusually high incidence of either a single cancer or a spectrum of cancers. The search for potential causes is complex, expensive and often inconclusive.

Years of exposure to a cancer-causing agent (carcinogen) may be necessary before a malignancy occurs. During that interval a person may move to another part of the country, and the link to the causative agent may be obscured. A factory producing carcinogens may close and leave behind toxic wastes that may pollute soil and water for many years.

If a manufacturing or commercial enterprise is suspected of releasing carcinogens into the air or water, affected residents and their families must battle lobbyists and corporate lawyers to prove their case.

In the 1970s, multiple cases of liver and bladder cancer among residents of Sand Mountain, a rich agricultural region of Northeast Alabama, were linked to the pesticide Heptachlor (now banned). Extensive aerial spraying of crops with Heptachlor led to accumulation of the chemical in the groundwater of the region. Samples of wellwater contained concentrations of the chemical that far exceeded "safe" limits. Cancer epidemiologists sometimes encountered resistance from residents who feared loss of jobs if they cooperated with the scientists. Extension of waterlines to homes from noncontaminated sources corrected the problem.

In late 2019, residents of four counties in Southwestern Pennsylvania demanded an investigation by state officials of a an unusually high incidence of Ewing sarcoma, a rare cancer of bone that typically affects teens to young adults. Thirty-one cases occurred in the four counties from 2006 to 2017. A spectrum of other cancers involving bone, muscle, liver and bone marrow affected young residents in the region. Residents linked the outbreak to the high concentration of fracking wells — more than 3,500 — in the counties. Industry officials denied any link. An extensive investigation is underway.

"Cancer Alley" defines a stretch along the Mississippi River that extends from Baton Rouge to the Gulf of Mexico. The land is home to dozens of petrochemical plants with additional plants awaiting approval. Studies by the EPA document high concentrations of cancer-causing chemicals in the region. Residents complain of air-pollution and point to a higher rate of a variety of cancers in their communities compared to other parts of Louisiana. Industry spokesmen deny any association between their emissions from their plants and malignant diseases.

States and counties show wide variations in the incidence of malignancies. Kentucky, West Virginia and Louisiana stand out in the mid-South for higher rates of cancer. Within a state, counties may show sharp differences in their cancer rates.

In the interval, 2012 to 2016, several counties in Tennessee exhibit high incidences of cancers in general. These counties include Marion, Sequatchie, and Meigs Counties and a band of counties along the Tennessee-Kentucky border, extending from Hancock to Scott Counties.

The maps permit comparisons of the incidence of specific types of cancer among states and counties within states. For example, during the same interval, striking differences are seen in the incidence of cancers of colon and rectum. Sequatchie and Grundy counties have a high incidence in our region.

Maps of other states show similar disparities in cancer rates among counties.



State cancer profiles for the interval 2012 to 2016 are accessible via interactive maps compiled by the National Cancer Institute and the Centers for Disease Control and Prevention at


The differences of cancer incidences within our state raise important questions:

* Are the differences due to contaminated ground water? If so, what are the possible sources of contamination? Is there a history of mining in the area that might contribute to toxic run-offs into nearby streams?

* Is air-quality a factor?

* Were the regions at one time the sites of chemical plants that dumped toxic wastes?

* If environmental factors are not related to the higher incidence of cancer in a county or region, are behavioral factors, such as smoking, to blame?

* Do higher cancer rates in a region correlate with obesity?

Our state's Department of Health is the logical agency to pursue research, which could provide answers to these important questions.

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Dr. Cliff Cleaveland / Staff file photo

Contact Clif Cleaveland at