Colorectal (Colon) Cancer and Asbestos Exposure

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Colorectal cancer is as a disease of the large intestine or rectum, and it is the second-leading cause of cancer-related deaths in the United States. Nearly 143,000 people in the United States were diagnosed with colon cancer in 2008, and nearly 53,000 died from the disease.

Medical research on the relationship between colorectal cancer and asbestos is mixed. Some studies suggest a definitive cause and effect culminating in higher colorectal cancer rates because of asbestos exposure.

Other studies show little statistical basis for such a claim. Cancers like mesothelioma and lung cancer can be caused by asbestos exposure.

Colorectal Cancer Evidence and Asbestos

Occupational exposure to asbestos was the impetus for a major cancer study between 1984 and 2004. Experts looked at 3,897 patients who were exposed at work to asbestos. They then reviewed the potential link between asbestos and various specific cancers and found that colorectal cancer was elevated among men who proved they were occupationally exposed to asbestos. Authors of the study said age, a history of smoking and other factors were adjusted in the results.

Another much older study of 632 insulation workers, an occupation well-known for asbestos exposure, yielded similar results. Workers who were evaluated entered the industry before 1943. Their health was monitored until 1962.

Data revealed 17 deaths were attributed to this cancer, suggesting that asbestos exposure increases the development of colorectal cancers. Authors of the study had expected 5.2 deaths from colon or rectum cancers based on the population.

Fast Fact: According to the Center for Disease Control and Prevention (CDC) in 2012, screenings for colorectal cancer are recommended for women and men beginning at the age of 50.

Conflicting Data

Despite scientific data supporting a link between colorectal cancer and asbestos exposure, conflicting studies suggest the opposite. According to one report, published in International Archives of Occupational and Environmental Health in 1994, researchers studied 261 cases of colon and rectal cancer and 183 control cases in southeast Michigan. Workers from occupations with historically known asbestos exposure were analyzed.

The authors said the data did not support a finding of a causal relationship. They acknowledge that links between asbestos exposure and colorectal cancer exist in other studies and reports but found contradicting evidence within the context of their study.

In addition, researchers who performed an in-depth analysis of different published reports involving 20 groups of asbestos-exposed individuals found similarly interesting results. The study, which was published in the American Journal of Epidemiology, found that one specific type of asbestos, amphibole asbestos, may potentially be associated with colorectal cancer, but may be as a result of an improper certification of cause of death. The authors reported data that suggests serpentine asbestos is not linked to an increased risk of colorectal cancer.

Further Evidence Needed

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Because of the mixed results of various studies of colorectal cancer and exposure to asbestos, researchers in this area agree that more studies are needed to determine a causal link. The need for further research does not infer that a link does not exist, but rather that researchers are unsure.

Completed studies account for only a small portion of the research conducted on colorectal cancer and asbestos exposure.

Additional Resources

  1. National Cancer Institute – Colon and Rectal Cancer. (n.p.). Retrieved from http://www.cancer.gov/cancertopics/types/colon-and-rectal
  2. Agency for Toxic Substances & Disease Registry – Health Effects. (2008 April 1). Retrieved from http://www.atsdr.cdc.gov/asbestos/asbestos/health_effects/
  3. Aliyu, O.A., Cullen, M. R. Evidence for Excess Colorectal Cancer Incidence among Asbestos-exposed Men in the Beta-Carotene and Retinol Efficacy Trial. American Journal of Epidemiology. (2005 November 1). Retrieved from http://aje.oxfordjournals.org/content/162/9/868.full
  4. Selikoff, I. MD, Churg, J. et. al. Asbestos Exposure and Neoplasia. The Journal of the American Medical Association. (1964 April 6) Retrieved from http://jama.ama-assn.org/content/188/1/22.full.pdf+html

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