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

Background: 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. Method: We reviewed the literature concerning cimetidine's potential anticancer activity, particularly with regard to gastro-intestinal cancers. Results: 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. Conclusion: 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.