Colorectal cancer is the third most commonly diagnosed cancer in the U.S. In 2008, the American Cancer Society estimates more than 148,800 new cases will be diagnosed in this country. It's the second leading cause of cancer death in the U.S., killing about 49,960 men and women this year.

The risk for colorectal cancer increases with age. More than 90 percent of cases are diagnosed after 50. Personal history of colorectal polyps or inflammatory bowel disease, or prior treatment for colorectal cancer also increases risk. African-Americans have the highest rates of occurrence and death from the cancer than any other racial group in the U.S. Research also suggests a diet high in red meats and processed meats, a sedentary lifestyle, obesity, smoking, excessive consumption of alcohol and having type 2 diabetes also increase the risk.

Another important risk factor for colorectal cancer is family history. The American Cancer Society estimates about 20 percent of Americans with colorectal cancer have at least one family member with the disease. Having one first-degree relative (mother, father, sister, brother or child) doubles the risk of developing the cancer. Having two or more relatives with the cancer increases risk by four times.

Family History and Colon Cancer Outcome

Researchers at Dana-Farber Cancer Institute in Boston wanted to find out if family history of colon cancer had any influence on treatment outcome for patients diagnosed with stage III colon cancer. In the recent study, nearly 18 percent of participants had at least one first-degree relative with the cancer.

The researchers found rates of cancer recurrence and death were significantly lower in patients with a family history of colon cancer compared to those without any family history. Cancer recurrence occurred in 27 percent of those with a family history and 35 percent of those without a family history. 22 percent of those with a family history died compared to 28 percent of patients in the no family history group. Researchers also found the more family members that were affected by colon cancer, the greater the patient's odds of survival.

Gastrointestinal Oncologist Jennifer Chan, M.D., M.P.H., is lead author of the study. She says investigators don't know why family history would be associated with lower recurrence and higher survival rates. Investigators would like to study the tumor biology and genetics of affected patients to determine what factors influence their outcome after treatment.

Not all researchers agree with the findings. Another recent study followed the outcome of women diagnosed with colorectal cancer in varying stages of the disease. Those researchers found patients who had one or more affected family members had a significantly decreased rate of survival compared to those without a family history.

For general information on colorectal cancer:

American Cancer Society

National Cancer Institute