Does cimetidine improve prospects for cancer patients?. A reappraisal of the evidence to date.

Evidence first appeared in 1988 that cimetidine as an adjuvant may improve the survival of severely ill gastro-intestinal cancer patients when given peri- or postoperatively. Since then, several studies have appeared which suggest an anticancer activity for cimetidine, although few attempts have been made to corroborate their findings in large, placebo-controlled, double-blind studies. We reviewed the literature concerning cimetidine's potential anticancer activity, particularly with regard to gastro-intestinal cancers. Most studies suggest that cimetidine may improve the outcome in cancer patients by a three-pronged mechanism involving (1) inhibition of cancer cell proliferation; (2) stimulation of the lymphocyte activity by inhibition of T cell suppressor function, and (3) inhibition of histamine's activity as a growth factor in tumours. Bearing in mind the experimental evidence, as well as the potential and excellent safety profile of cimetidine, more studies are required and justified to clarify cimetidine's protherapeutic activity.