The study including 414 patients aged over 60 years suffering lung esophageal, gastric and colorectal cancer was carried out to assess the possibility of preventing postoperative complications. Preoperative preparation, anesthesiologic medication and drug treatment in the early postoperative period included vitamins, eleutherococcus, sodium oxybutyrate, retabolil, splenin, curantyl, heparin, panangin, sulfalen and trichopol. In that group, the overall postoperative complication rate was 1.5 times lower and that of purulent complications, cardiovascular disorders, pneumonia and pancreatitis--2 times lower than those in 642 controls. The duration of postoperative stay in the hospital was shorter and the postoperative lethality tended to decrease. Topical treatment with methylsiloxane-immobilized gentamycin and 5-fluorouracil was shown to prevent development of purulent complications and pancreatitis.