Optimal time interval from surgery to adjuvant chemotherapy in gastric cancer

The effect of adjuvant chemotherapy (AC) for resected gastric cancer is well established; however, delays in treatment and its impact on clinical outcomes have not yet been determined. The current study analyzed the survival rates based on time interval (TI) between surgery and AC administration to evaluate a potential association between the two variables. Patients diagnosed with stage II-III gastric adenocarcinoma between 2009 and 2016 at the Kyung Hee University Hospital were included. Patients' data including demographics, TNM stage, types of AC, and TI retrospectively collected from surgery to the start of AC. Patients were dichotomized based on the TI, which was predetermined at 3, 4, 5, 6, 7 or 8 weeks. Median disease-free survival (DFS) and overall survival (OS) were analyzed according to TI. In total, 172 patients were identified. The median follow-up duration was 40.8 (3-109) months. The median TI was 4.1 (2.1-9.8) weeks. DFS in patients with TI >= 4 weeks (n=106, 61.6%) was significantly lower compared with patients with TI <4 weeks (n=66, 38.4%), with a median DFS of TI < vs. >= 4 weeks of 8.1 vs. 6.0 years [hazard ratio (HR)=1.80, 95% confidence interval (CI): 1.067-3.045, P=0.0277]. OS was also significantly reduced in patients with TI >= 4 weeks, favoring TI <4 weeks [median OS of TI < vs. >= 4 weeks: Not reached (NR) vs. 7.0 years, HR=2.15, 95% CI: 1.173-3.939, P=0.0133]. Other predetermined TIs were not associated with survival outcomes. The current study demonstrated that AC within 4 weeks of surgery should be recommended for gastric cancer, and delays of >4 weeks may be detrimental to patients' survival.