A family history of colon cancer raises the risk of developing the disease, but it also appears to be associated with a better prognosis, researchers reported.
Patients with stage III colon cancer who had a family history of the disease had significantly fewer recurrences and significantly better mortality 5 years after their diagnosis than did those with no family history of colon cancer in a study of over 1,000 patients.
This apparent benefit became stronger as the number of affected family members increased, said Dr. Jennifer A. Chan of the Dana-Farber Cancer Institute, Boston, and her associates. They assessed the influence of family history on survival using data on 1,087 patients with colon cancer who participated in a National Cancer Institute-sponsored clinical trial of adjuvant chemotherapy. All patients had undergone complete surgical resection of the primary tumor in 1999–2001, and all had regional lymph node metastases but no distant metastases at that time.
A total of 195 of the patients reported a family history of colon cancer in first-degree relatives. However, none had the hereditary colorectal cancer syndromes of familial adenomatous polyposis or hereditary nonpolyposis colorectal cancer. After a mean of 5 years of follow-up, cancer recurrence or death occurred in 57 of these patients with a family history of the disease (29%), compared with 343 of the patients who did not have a family history (38%).
Cancer recurrence or death occurred in 30% of patients with one affected relative and in 23% of patients with two or more affected relatives, compared with 38% of those who had no affected relatives, the authors said (JAMA 2008;299:2515-23).
This protective effect persisted when the data were adjusted to account for numerous predictors of cancer recurrence and survival, including the possibility that patients with a family history may have had earlier tumor detection precisely because of this history. These patients all were subjects in a rigorously controlled, randomized clinical trial, so they all had the same disease stage, the same treatment and follow-up care, and the same extensive background data on possible confounding factors. The investigators noted that their findings “support the hypothesis that a relatively common … genetic predisposition may not only influence co-lorectal cancer risk but also patient survival.”