A study of cancer of the breast and other sites in women after total colectomy and ileostomy for non-malignant disorders.

To assess the role in breast-cancer aetiology of oestrogenic substances apparently produced by intestinal bacteria from faecal residues associated with a high-fat diet and other absorbable and possibly carcinogenic colonic substances, cancer incidence and mortality were studied in 2425 women in the UK who had previously had total colectomy and terminal ileostomy, mostly for ulcerative colitis for Crohn's disease. The incidence of breast cancer in this group of women was no lower than would be expected, although there was a slight deficiency of deaths from this cause. These findings suggest that, at least in adult life, the colon is not involved in the aetiology of breast cancer. There were pronounced excesses of rectal and bile-duct cancers in ulcerative colitis patients despite previous colectomy