Faecal bile acids and clostridia in patients with breast cancer.

We have studied 30 patients presenting with breast cancer and 36 control patients admitted to hospital for minor surgery. Stool specimens were obtained for bile acid analysis and bacterial nuclear dehydrogenation activity (NDC) estimation. The mean total faecal bile acid (FBA) concentration (mumol/g) in patients with breast cancer was 15.6 /+- 1.8 s.e., significantly lower than for control patients (20.5 /+- 1.9). NDC were isolated from the faeces of 58% of breast cancer patients an 15% of control patients, this difference being statistically highly significant (P less than 0.005). Increased bile-acid degradation by bacteria in the large bowel may explain the reduced FBA concentration in patients with breast cancer. Increased NDC isolation in breast-cancer patients suggests that oestrogen production in the colon may play a role in the aetiogy of breast cancer in some patients.