Three people are diagnosed with different types of cancer. One is a lifelong smoker and has
lung cancer, one has active Crohn disease and has colorectal cancer, and the other is a
farmer with newly diagnosed melanoma. What do these individuals have in common?
Pathophysiologic
Cancer results from predominant somatic and environmental causes. However, assessing
genetic or hereditary causes is a bit difficult unless for single-gene causes that are highly
penetrant. It is worth noting that family studies only provide partial information as far as this is
concerned since family members share lifestyles and diets. Classically, twin studies have been
useful in disentangling the impacts of environment and heredity on disease etiology.
Environmental and genetic components in melanoma, colorectal cancer, and lung cancer can be
estimated by comparing risks in other family members (Hemminki et al., 2001). The types of
cancers the three individuals are suffering from (lung cancer, melanoma, and colorectal cancer)
are considered to be the top three cancers, contributing to forty two percent of all cancers.
The genetic component of colorectal and colon cancers ranges at ten percent and eighteen
percent for melanoma. If assortative mating is considered vital for cancer liability, then
hereditary estimates may become an underestimation of the real genetic impacts. Non-shared
environmental impact for melanoma and colorectal cancer is 67-68 percent and seventy one
percent for lung cancer (Brose et al., 2002). Childhood and shared environments are equally
significant in melanoma and colorectal cancer. However, no childhood effect is observed in lung
cancer.
PATHOPHYSIOLOGIC 2
The three types of cancers are as a result of inappropriate lifestyles. The farmer is
suffering from melanoma due to excessive exposure to UV radiations. If he had taken proper
measures, he would not be suffering. The person suffering from lung cancer is as a result of
carcinogens present in the cigarette (Jemal et al., 2010). Finally, Crohn’s disease is triggered by
cigarette smoke and environmental factors. The disease gradually predisposes an individual to
colorectal cancer. Therefore, leading a healthy lifestyle can prevent the three types of cancers.
PATHOPHYSIOLOGIC 3
References
Brose, M. S., Volpe, P., Feldman, M., Kumar, M., Rishi, I., Gerrero, R., & Weber, B. L. (2002).
BRAF and RAS mutations in human lung cancer and melanoma. Cancer research,
62(23), 6997-7000.
Hemminki, K., Lönnstedt, I., Vaittinen, P., & Lichtenstein, P. (2001). Estimation of genetic and
environmental components in colorectal and lung cancer and melanoma. Genetic
epidemiology, 20(1), 107-116.
Jemal, A., Siegel, R., Xu, J., & Ward, E. (2010). Cancer statistics, 2010. CA: a cancer journal
for clinicians, 60(5), 277-300.