In the first study, epidemiologists surveyed 424 patients with new cases of colon cancer and 414 community controls, selected by random-digit dialing. Frequent constipation ("feeling constipated to the point of having to take something" at least weekly in the previous 10 years) was associated with an adjusted relative risk for cancer of 4.4. In a second study, Harvard University researchers found that butyrate, a fermentation breakdown product of fiber, induces expression of p21, a tumor suppressor gene in colon cancer cells that causes them to cease growing.

Comment: The epidemiologic study confirms a previous meta-analysis showing constipation to be strongly associated with colon cancer, but not with rectal cancer. Perhaps the strongest study to date, it used randomly selected community controls, defined constipation precisely, asked about long-term patterns of constipation, and adjusted for many confounding variables. Although lack of dietary fiber is an important cause of constipation, the increased risk of colon cancer with constipation was independent of fiber intake. Fiber's protective effect has been attributed to reduced colonic exposure to mutagenic substances because of faster stool transit times, but the Harvard study suggests that fiber may also increase natural tumor suppression. --AL Komaroff

Published in Journal Watch July 14, 1998

Source

Jacobs EJ and White E Constipation, laxative use, and colon cancer among middle-aged adults Epidemiology 1998 Jul; 9:385-391.[Medline abstract][Download citation]

Archer SY et al P21[SUPER]WAF1 is required for butyrate-mediated growth inhibition of human colon cancer cells Proc Nat Acad Sci USA 1998 Jun 9; 95:6791-6796.[Original article][Medline abstract][Download citation]