RESUMO
BACKGROUND: Pilot studies have shown that histamine H2 receptor antagonists augment the natural immunity against cancer in colorectal and gastric cancer by enhancing lymphocytic infiltration in the tumors. However, a study of adjuvant ranitidine failed to show a significant benefit in colorectal cancer, possibly because of the immunosuppression exerted by blood transfusion and post-operative infections. The pre-operative use of H2 receptor antagonists may therefore be of greater benefit. Except for a pilot study using cimetidine, there are no trials that have evaluated the effect of pre-operative H2 receptor antagonists on tumor infiltrating lymphocytes in colorectal cancer. OBJECTIVE: To evaluate the efficacy of famotidine in augmenting tumor infiltrating lymphocytes in colorectal cancer. STUDY DESIGN: Double blind, placebo controlled, prospective randomized study. METHODS: Twenty-three patients with resectable colorectal cancer were randomized to receive famotidine (n = 11) or placebo (n = 12). Famotidine was given for 1 week pre-operatively in a dose of 40 mg per day p.o. After resection, the specimens were analyzed histologically for lymphocytic infiltration by a pathologist blinded to the two groups. Lymphocytic infiltration more than 50 cells per high power field, involving more than 50% of the tumor-normal tissue interface was considered significant. RESULTS: The two groups were comparable for age, gender, pre-operative carcino embryonic antigen (CEA) levels and pathological stage. Significant lymphocytic infiltration was seen in 63.6% (7 of 11) patients in the study group compared to only 8.5% (1 of 12) patients in the placebo group (P = 0.005). Despite fewer recurrences and a longer survival in the study group, the difference was not significant. CONCLUSION: This study shows that pre-operative famotidine may significantly enhance lymphocytic infiltration in colorectal cancer and may have potential for use as an anticancer agent in colorectal cancer.
