Impact of splenectomy and immunochemotherapy on survival following gastrectomy for carcinoma: Covariate interaction with immunosuppressive acidic protein, a serum marker for the host immune system

The role of the spleen in tumor immunology is still controversial in that i t can either enhance or suppress the antitumor immune response depending on the tumor-bearing host. To clarify this biphasic effect of the spleen, a c linical evaluation of splenectomy in conjunction with immunotherapy and the host immune status was performed in gastric cancer patients. The effect of splenectomy and immunotherapy in 253 gastric cancer patients enrolled in a prospective randomized trial (SIP) was analyzed using the Cox's proportion al hazards model in terms of the covariate interaction of the preoperative immunosuppressive acidic protein (IAP) level. In patients with high IAP lev els (>580 mu g/ml) with predicted negative antitumor immune reactions, sple nectomy improved the prognosis. In patients with lower IAP values, converse ly, the preservation of the spleen and immunotherapy demonstrated a signifi cant benefit to survival. The spleen was shown to have a biphasic activity in terms of its antitumor immune response depending on the IAP level of the patient. The effect of immunotherapy is significantly influenced by the ac tivity of spleen cells. The preoperative IAP level is therefore considered to be a possible indicator for the effectiveness of splenectomy and immunot herapy in curatively resected gastric cancer patients.