Appendectomy, appendicitis, and large bowel cancer.

A cohort of 167,561 persons who received multiphasic health checkups were followed up for cancer development. A history of appendectomy showed slightly negative nonsignificant associations with the development of cancer of the colon, rectum, and all sites combined. By inference, the relation of appendicitis with these cancers was also inverse. Upper 95% confidence limits were compatible only with small positive associations of appendectomy and appendicitis with these cancers. These data do not support the view that removing the appendix increases cancer risk by diminishing immunocompetency. A link between appendicitis and large bowel cancer has been noted in intersociety correlations and has been hypothesized to be due to prevention of both by a high-fiber diet. However, appendicitis does not appear to be a useful predictor of large bowel cancer within a developed society.