GUT BACTERIA AND ÆTIOLOGY OF CANCER OF THE BREAST

The geographical variations in the incidence of breast cancer seem to be correlated with variation in the fat content of the diet. There is also strong evidence for a direct role for œstrogens in the ætiology of breast cancer. We have already postulated that gut bacteria can produce œstrogens from the biliary steroids present in the colon. Since the amount of biliary steroid found in fæces is correlated with the amount of fat in the diet, this could explain the relation between the amount of dietary fat and the incidence of breast cancer. Gut bacteria have been shown to be able to produce steroidal oestrogens from bile-acids and cholesterol derivatives in vitro.