Timing of Adjuvant S‐1 Chemotherapy and Survival After Pancreatectomy for Pancreatic Cancer: An Ancillary Analysis of the <scp>JASPAC</scp> 01 Trial

BACKGROUND: Relationship between timing of initiating adjuvant chemotherapy (AC) and clinical outcomes after surgery for pancreatic cancer remains controversial. METHODS: In this ancillary analysis of the JASPAC 01 trial, 187 patients were classified according to the interval between surgery and chemotherapy initiation to Early (< 6 weeks, n = 45), Standard (6-8 weeks, n = 70), and Delayed (> 8 weeks, n = 72). Overall survival (OS) and relapse-free survival (RFS) were analyzed. RESULTS: Baseline characteristics were comparable among three groups. The Standard group showed significantly longer OS than the Early group (median, 66 vs. 37 months; HR 0.61, 95% CI 0.38-0.99; p = 0.041), and relatively longer OS compared with the Delayed group (median, 45 months; HR 0.68, 95% CI 0.44-1.05; p = 0.077). RFS was longer in the Standard group (median, 46 months) compared with the Early group (20 months; HR 0.61, 95% CI 0.38-0.99; p = 0.040) and the Delayed group (20 months; HR 0.59, 95% CI 0.39-0.89; p = 0.011). Multivariate analysis identified operative procedure, R1 resection, lymph node metastasis, and nonstandard initiation (< 6 or > 8 weeks) as independent adverse prognostic factors. CONCLUSIONS: Initiation of S-1 AC at 6-8 weeks after pancreatectomy was associated with favorable survival outcomes.