Background. In Japan since the 1960s, patients with gastric cancer have routinely had splenectomy combined with gastrectomy to ensure that lymph node dissection is complete. However, the influence of splenectomy on long-term immunity is unclear.METHODS: Forty-nine gastric cancer patients who underwent total gastrectomy for cure with ( n = 25) and without ( n = 24) splenectomy were assessed for immunologic function, including the proportion of lymphocyte subsets, purified protein derivative from tuberculin (PPD) response, natural killer (NK) activity, and phytohemagglutinin (PHA) response.RESULTS: Peripheral T-cell mediated functions, e.g., PPD and PHA response, were significantly suppressed in patients who underwent gastrectomy with splenectomy compared with those who had gastrectomy alone. Decreased T-cell subsets (CD 3+, 4+, 8+) and increased NK cell subsets (CD 16+, 57+) were observed in patients who underwent splenectomy. Patients who did not undergo splenectomy had immunologic responses within the normal range.CONCLUSIONS: Splenectomy decreased T-cell mediated responses over the long term. As a potential means to co-rrect this T-cell dysfunction in patients with splenectomy, splenic autotransplantation should be considered in future research.