BACKGROUND: How the interval between surgery and S-1 adjuvant chemotherapy (ACT), and S-1 relative dose intensity (RDI) affect prognosis in patients with stage II/III gastric cancer who undergo gastrectomy with D2 lymph node dissection followed by S-1 ACT is unclear. METHODS: We enrolled 95 patients with histopathologically confirmed gastric adenocarcinoma treated with gastrectomy with D2 dissection, followed by S-1 ACT. RESULTS: Per ROC analysis, we used 32 days as the optimal cut-off interval to divide patients into the delayed group (started ACT ≥ 32 days) and the non-delayed group ( < 32 days). Their 5-year overall survival (OS) rates differed significantly (delayed: 54.2%, non-delayed: 85.4%; P < 0.0001). Per ROC analysis of patients without recurrence within 1 year post-surgery, patients were divided into the high RDI (RDIHigh; ≥ 64.6%) and low RDI (RDILow; < 64.6%) groups. Their 5-year OS rates differed significantly (RDIHigh: 76.9%, RDILow: 63.7%; P = 0.012). In multivariate analysis, RDI and interval before starting ACT were independent prognostic indicators. Five- year OS rates by subgroups were RDIHigh/non-delayed: 84.0%, RDIHigh/delayed: 66.8%, RDILow/non-delayed: 100%, and RDILow/delayed: 48.2% (P < 0.0001). CONCLUSIONS: Early initiation and sufficient RDI for S-1 ACT can improve the prognosis of patients with stage II/III gastric cancer.
BACKGROUND: How the interval between surgery and S-1 adjuvant chemotherapy (ACT), and S-1 relative dose intensity (RDI) affect prognosis in patients with stage II/III gastric cancer who undergo gastrectomy with D2 lymph node dissection followed by S-1 ACT is unclear. METHODS: We enrolled 95 patients with histopathologically confirmed gastric adenocarcinoma treated with gastrectomy with D2 dissection, followed by S-1 ACT. RESULTS: Per ROC analysis, we used 32 days as the optimal cut-off interval to divide patients into the delayed group (started ACT ≥ 32 days) and the non-delayed group ( < 32 days). Their 5-year overall survival (OS) rates differed significantly (delayed: 54.2%, non-delayed: 85.4%; P < 0.0001). Per ROC analysis of patients without recurrence within 1 year post-surgery, patients were divided into the high RDI (RDIHigh; ≥ 64.6%) and low RDI (RDILow; < 64.6%) groups. Their 5-year OS rates differed significantly (RDIHigh: 76.9%, RDILow: 63.7%; P = 0.012). In multivariate analysis, RDI and interval before starting ACT were independent prognostic indicators. Five- year OS rates by subgroups were RDIHigh/non-delayed: 84.0%, RDIHigh/delayed: 66.8%, RDILow/non-delayed: 100%, and RDILow/delayed: 48.2% (P < 0.0001). CONCLUSIONS: Early initiation and sufficient RDI for S-1 ACT can improve the prognosis of patients with stage II/III gastric cancer.