Time to initiation or duration of S-1 adjuvant chemotherapy; which really impacts on survival in stage II and III gastric cancer?

Abstract

Surgical resection with S-1 adjuvant chemotherapy (AC) is the standard of care for stage II-III gastric cancer (GC). However, it is unclear if time to initiation and duration of S-1 AC impact on survival. A multi-institutional GC database identified 498 patients who were treated with S-1 AC after D2 or more extended radical surgery for stage II-III gastric cancer. Patients were divided into four groups according to the interval between surgery and initiation of AC and the duration of AC as follows: group A (n=226), who received AC earlier (≤6weeks) and for longer (≥6months) after surgery; group B (n=160), who received AC later (>6weeks) and for longer after surgery; group C (n=46), who received AC earlier but for a shorter period (<6months) after surgery; and group D (n=66), who received AC later and for a shorter period after surgery. Prognostic factors for overall survival (OS) were investigated using multivariate analysis. The 5-year OS was 69.5%. Pathological stage II disease (hazard ratio (HR), 0.334; 95% confidence interval (CI), 0.215-0.499), with an OS of 85.8% versus 60.5% for stage III disease, as well as a longer duration (≥6months) of S-1 (HR, 0.498; 95% CI, 0.355-0.706), with an OS of 74.3% versus 53.0% for a shorter duration (<6months) of S-1, were identified as significant prognostic factors for long-term survival. Time to initiation was not associated with OS. A duration of S-1 AC of ≥6months, but not time to initiation within 6weeks, impacts on OS in stage II-III gastric cancer.