Introduction: International studies on preoperative risk factors of postoperative complications after gastrectomy for gastric cancer are few, and studies done in a population-based setting or using standardized definitions are lacking. Gastrectomy for gastric cancer is characterized by high complication rates and mortality, and identifying the risk factors for postoperative complications and mortality enables to improve the postoperative outcomes.

Materials and methods: This nationwide population-based cohort study is based on the Finnish National Esophago-Gastric Cancer Cohort, and it included all patients undergoing gastric cancer surgery in Finland during 2005-2016 aged 18 years or older. The Esophagectomy Complications Consensus Group's (ECCG) standardized list of complications was used for describing different types of postoperative outcomes.

Results: This study analyzed a total of 1993 patients. The results suggested that of potential risk factors, higher ASA-class, and advanced tumor stage increased the risk of major postoperative complications after gastrectomy for gastric cancer, whereas age ≥70 years and distal tumor location may be protective factors. The results suggested that older age, higher ASA-class, comorbidity, and advanced tumor stage were risk factors for 90-day mortality. Older age seemed to be a risk factor for 90-day mortality, whereas it seemed to protect from major postoperative complications and 90-day reoperations.

Conclusions: Higher ASA-class, and advanced tumor stage were risk factors for major complications after gastrectomy for gastric cancer, while older age and distal tumor location seemed to be protective factors.