BackgroundElderly gastric cancer patients (EGCPs) require treatment according to not just the stage of their cancer, but also to their general condition and organ function, and rather than full treatment, the appropriate amount of treatment is necessary.MethodsA total of 425 patients who underwent gastrectomy for primary gastric cancer in our institution between April 2013 and March 2020 were classified by age into two groups: elderly patients (EP, age ≥ 80 years, n = 89); and younger patients (YP, age < 80 years, n = 336). The preoperative, intraoperative, and postoperative conditions of the two groups were then compared. Propensity score matching (PSM) was performed, and factors affecting complications and survival outcomes were examined in detail. In addition, the necessary treatment strategy for EGCPs in the preoperative, intraoperative, and postoperative periods was investigated.ResultsOf the preoperative factors, American Society of Anesthesiologists physical status (ASA-PS) was significantly higher, and respiratory function was significantly lower in the EP group than in the YP group, and the prognostic nutritional index (PNI) also tended to be lower. Of the intraoperative factors, there was no difference in the level of lymph node dissection. However, the EP group had significantly higher rates of postoperative pneumonia and anastomotic leakage. Of the postoperative factors, on simple comparison, postoperative long-term outcomes of the EP group were significantly worse (63.8% vs. 85.4%, p < 0.001), but there was no significant difference in disease-specific survival (DSS), and the DSS survival curves after PSM were almost identical, indicating that the survival rate in the EP group was decreased by death from other disease. Though the survival rate of laparoscopic surgery was significantly better than that of open surgery in the YP group, there was a significantly lower rate of postoperative complications in the EP group after PSM.ConclusionsIn EGCPs, one needs to be aware of short-term complications such as pneumonia and anastomotic leakage due to respiratory dysfunction and malnutrition that are present before surgery. Furthermore, to suppress deaths from other diseases that reduce postoperative survival rates, prevention of postoperative complications (particularly pneumonia) through minimally invasive surgery can be effective.