Efficacy and safety of neoadjuvant S-1-based chemoradiotherapy in resectable and borderline- resectable pancreatic cancer: A long-term follow-up study

Background/Objectives: This study aimed to evaluate the safety, efficacy, and long-term outcomes of S-1-based neoadjuvant chemoradiotherapy (NACRT) in patients with resectable or borderline-resectable pancreatic ductal adenocarcinoma (PDAC). Methods This retrospective study included patients with PDAC who underwent S-1-based NACRT at our institute between 2010 and 2017. Results Forty patients were included in the study, including 15 (37.5%) with resectable PDAC and 25 (62.5%) with borderline-resectable PDAC. The NACRT completion and resection rates were 85.0% (n = 34) and 67.5% (n = 27), respectively. Several grade 3 adverse events were observed, including leukopenia (25.0%), anorexia (17.5%), neutropenia (10.0%), thrombocytopenia (7.5%), febrile neutropenia (2.5%), elevated aspartate aminotransferase/alanine aminotransferase (2.5%) levels, and hyponatremia (2.5%). The R0 resection rate was 70.4% (n = 19/27) in patients who underwent pancreatectomy. Grades 1, 2, and 3 according to the College of American Pathologists grading system were observed in 1 (3.7%), 12 (44.4%), and 14 (51.9%) patients, respectively. Over a median follow-up period of 32.9 months (interquartile range, 9.1–68.0), the 1-, 3-, and 5-year OS rates were 81.4%, 45.5%, and 30.3%, respectively, in the intention-to-treat analysis. In the curative-intent surgery cohort (n = 27), the 1-, 3-, and 5-year OS rates were 88.9%, 48.2%, and 37.0%, respectively. Conclusions S-1-based NACRT is safe and yields acceptable long-term outcomes for patients with resectable or borderline-resectable PDAC.