Impact of Neoadjuvant Chemotherapy with Gemcitabine Plus S-1 in Patients with Resectable Pancreatic Ductal Adenocarcinoma

Background/Objectives: Although neoadjuvant chemotherapy (NAC) is not universally recommended for resectable pancreatic ductal adenocarcinoma (PDAC), NAC with gemcitabine plus S-1 (NAC-GS) has become a commonly used regimen for resectable PDAC in Japan. Furthermore, the impact of achieving textbook outcomes (TO) in patients receiving NAC-GS remains unclear. Methods: This retrospective study included 265 patients who were diagnosed with resectable PDAC at our institution between January 2009 and December 2023. Patients were categorized into two groups: the NAC-GS group (n = 81; 2019–2023) and the upfront surgery (UFS) group (n = 164; 2009–2018). After comparing the clinical outcomes between groups, multivariate analyses for survival were performed. Additionally, outcomes stratified by the achievement of the modified TO were analyzed in the NAC-GS group. Results: The completion rate of NAC-GS was 90.1%. Patients in the NAC-GS group exhibited significantly longer survival than those in the UFS group (2-year recurrence-free survival: 61.4% vs. 37.9%, p < 0.01; 2-year overall survival: 83.2% vs. 61.2%, p < 0.01). Multivariate analyses identified lymph node metastasis, NAC-GS induction, and completion of adjuvant chemotherapy as factors significantly associated with improved survival. Moreover, among patients who received NAC-GS, those who achieved modified TO demonstrated significantly longer survival than those who did not. Conclusions: This study demonstrated the clinical efficacy of NAC-GS in patients with resectable PDAC. Induction of NAC-GS was significantly associated with improved long-term outcomes. In multidisciplinary treatment strategies for PDAC, achieving a modified TO may lead to improved survival of patients undergoing NAC-GS.