Background Postoperative inflammation is associated with cancer progression in several cancers. However, the prognostic significance of postoperative fever remains unclear in gastric cancer patients.

Methods We enrolled 442 patients with a histopathological diagnosis of gastric adenocarcinoma who underwent curative surgery.

Results The mean duration of postoperative fever ≥ 37°C was 8.7 days (range: 0–186 days) and significantly longer in patients with advanced gastric cancer, venous invasion, and open or total gastrectomy vs. patients with early gastric cancer (P = 0.0072), no venous invasion (P = 0.025), laparoscopic gastrectomy (P = 0.027), and either proximal or distal partial gastrectomy (P = 0.0015). Five-year overall survival rates were 69.5% vs. 83.6% in the prolonged postoperative fever group (≥ 6 days of ≥ 37°C) vs. the nonprolonged group (< 6 days of ≥ 37°C), respectively (P = 0.0008). In patients without Clavien-Dindo classification postoperative infectious complications grade ≥ 2, 5-year overall survival was 69.7% vs. 84.0% in patients with prolonged postoperative fever vs. those without, respectively (P = 0.0067). Five-year disease-specific survival was 85.9% vs. 93.1% in patients with prolonged fever vs. those without, respectively (P = 0.041). Multivariate analysis indicated that postoperative fever was an independent prognostic indicator.

Conclusion Postoperative fever ≥ 37°C duration may be useful in predicting prognosis in gastric cancer patients.