June 10, 2008
American Cancer Society, Inc.

Research Examines Links Between Family History and Colon Cancer Survival

Numerous studies have shown your risk of getting colon cancer is higher if you have a first-degree family member who had the disease. New research shows that your chances of surviving the disease may be influenced in part by your family ties, too.

A recent study published in the Journal of the American Medical Association and led by researchers from the Dana-Farber Cancer Institute in Boston found that compared to patients with no family history of the disease, patients with stage III colon cancer treated with chemotherapy had a 28% lower risk for cancer recurrence or death if their family members had had the cancer. And the more first-degree family members with the disease a person has, the better a person's chance for survival, according to the data. Patients with 2 or more affected relatives were at a 51% lower risk for death or recurrence.

"We have long known that individuals with a family history of colorectal cancer have a higher risk of developing the disease," said Durado Brooks, MD, MPH, American Cancer Society Director of Prostate and Colorectal Cancer. "This study determined that individuals who had a family history of colon or rectal cancer actually had a better response [to treatment] -- less chance of death from colorectal cancer or a return of the disease -- than those who do not have a family history of the disease."

Approximately 20% of people who develop colon cancer are related to someone with the disease, and people with first-degree relatives who have had the disease are at an increased risk. For more information on this topic, see Colorectal Cancer: Early Detection.

Among 1087 stage III colon cancer patients in the study group, 195 (17.9%) had a first-degree relative with colon cancer; of that group, 57 (29%) died or had a cancer recurrence compared with 343 of 892 (38%) patients who didn't have a family history of the disease. The patients were enrolled in the National Cancer Institute-sponsored Cancer and Leukemia Group B (CALGB) trial from April 1999 until May 2001, and were followed until March 2007.

A Closer Look at the Data

In addition to collecting family tree information, the Dana-Farber researchers also examined tumors from a subset of patients to investigate whether the improved survival in those with a family history was related to having a (relatively) common form of hereditary colon cancer. They didn't find a correlation.

"This study raises important questions regarding which of the molecular and/or genetic differences that we see in colorectal cancer may help mediate the response to chemotherapy," said Brooks. "This could open new avenues of exploration for treating the disease based on specific findings in a patient's tumor cells at the time of diagnosis."

The researchers also investigated whether tumor size or stage played a role in survival. They hypothesized that patients with a family history of colorectal cancer might be more likely to get screened for the disease, finding tumors earlier, and thus, more likely to have a better prognosis. Excluding patients with smaller tumors didn't appear to affect their results, however.

Combat Risk Through Regular Screening

While it's certainly good news that patients with a family history of colon cancer seem to respond well to chemotherapy when they receive it, one-third had a recurrence or died during the study period.

If you catch colorectal cancer early, you stand a good chance of fighting it. Regular screening is the best way to control your risk. Some screening tests may even be able to prevent colorectal cancer entirely, by finding potentially dangerous polyps in the colon before they become cancerous.

The American Cancer Society recommends regular screening for colorectal cancer for all men and women starting at age 50. People with a family history of the disease are encouraged to begin screening at a younger age.

Unfortunately, many people fail to get screened. According to a new study from Johns Hopkins University and the University of Maryland, African Americans with a family history of colorectal cancer realized that their risk was high but were actually less likely to get screened compared to those without a family history of the disease. That suggests that other factors besides how well people understand their risk may be playing a role in determining whether someone seeks out preventative care.

The study, which was based on behavioral health data from 580 African Americans taking part in the 2002 Maryland Cancer Survey (MCS), found that the biggest predictor of whether a person would get screened was whether their physician recommended it, regardless of whether a person had a family history of colon cancer.

More research is needed to investigate what might be behind these low screening numbers, especially given that African Americans have the highest rate of colorectal cancer incidence and death of all racial groups in the United States. For more information on colon cancer, see our detailed guide. For more information about screening, see our guidelines.