The Medical Minute: Colorectal cancer and your family

April 28, 2009

By Thomas J. McGarrity and Maria Baker

Colorectal cancer is the second leading cause of cancer death for men and women in the United States. The average lifetime risk of developing colorectal cancer is approximately 6 percent. The incidence and death rate from colorectal cancer for Pennsylvanians is among the highest in the country. Because the risk of colorectal cancer is so significant, routine screening for colorectal cancer is recommended. Colonoscopy is the preferred screening tool and is recommended for men and women beginning at age 50 if they have no additional risk factors. Colorectal cancer is known to develop from precancerous polyps, so removing these precancerous polyps is an effective strategy to prevent the development of cancer. Screening also will detect asymptomatic early stage cancers, which can be cured surgically. Unfortunately more than half of colorectal cancers in Pennsylvania are late-stage diseases. It has been shown that a major factor determining whether a person is screened for colorectal cancer is a recommendation by the primary physician.

The burden of this disease is not shared equally. Family medical history is an important risk factor for the development of colorectal cancer. In approximately 30 percent of patients, there is a family history of colorectal cancer, and the incidence of this disease increases with the occurrence of colorectal cancer within your family. If you have been diagnosed with colorectal cancer, your closest family members have a two- to three-fold risk of developing colorectal cancer compared to the general population, and more aggressive screening methods are indicated. The American Cancer Society has made consistent recommendations that all first-degree relatives of a person with colorectal cancer begin screening at age 40 or 10 years before the earliest case in the family.

Approximately 5 to 10 percent of colorectal cancer is due to an inherited (genetic) predisposition to cancer. Certain cancers can cluster in some families. For instance, a personal history of ovarian or endometrial cancer before age 60 increases the risk for development of colorectal cancer. Colorectal cancer screening in these persons also should begin at age 40 years and be repeated every five years. Families with a strong cancer history would benefit from the advice of a cancer genetic counselor, an expert who can assess and interpret the family history as it relates to the risk of cancer and integrates this information into patient care recommendations. Effective screening strategies have been devised for these individuals. The Human Genome Project has resulted in numerous discoveries regarding the influence of heredity on cancer risk. Genetic testing, usually on a blood sample, can be done under the guidance of a cancer genetic counselor. To find a cancer genetic counselor in your area, visit The red flags that suggest a familial cancer predisposition syndrome include the early onset of common cancers (for colon cancer, younger than 50 years), multiple types of cancer within the family (colon, uterine, ovarian, etc.) and multiple family members with cancer. Ultimately the best cancer care involves treating the individual with cancer and caring for all family members at increased risk to develop cancer.

Racial differences also increase the risk for colorectal cancer. African-Americans have the highest incidence and mortality of colorectal cancer in the United States. They also appear to have an increased incidence of right-sided colorectal polyps and cancers, which are more difficult to detect by current screening strategies. For this reason, the American College of Gastroenterology recommends routine screening for all African-Americans beginning at age 45 instead of age 50. Race-specific differences in the natural history of colorectal cancer point to the need for continued research to improve screening and protection for all Pennsylvanians from this dreaded disease.

We recommend all Pennsylvanians have a dialogue with their primary care physicians to advocate for themselves and their families. Working together with your family physician, you can reduce the burden of cancer for yourself and your loved ones.

Thomas J. McGarrity is chief, division of gastroenterology, Penn State Milton S. Hershey Medical Center; Maria Baker is genetic counselor, medical geneticist, Penn State Hershey Cancer Institute.

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Last Updated July 22, 2015