Comparison with Short- and Long-term Neoadjuvant Chemoradiotherapy for Resectable and Borderline Resectable Pancreatic Adenocarcinoma

Abstract

Introduction: The indications of preoperative treatment for resectable (R) borderline resectable (BR) pancreatic ductal adenocarcinoma (PDAC) are still obscure, and the protocol has not yet been standardized. Method: The patients were divided into R, BR with venous involvement (BR-V) according to the 2019 NCCN guidelines. Between September 2009 and May 2016, short neoadjuvant chemoradiotherapy (NACRT) (3Gy x 10fr.+S-1) in 2 weeks was given to patients with R(n=33), BR-V(n=19). Subsequently, since June 2016, long NACRT (2Gy x 25fr.+S-1) in 5 weeks was given to patients with R(n=51) and BR-V(n=14) PDAC. Results: There was no significant difference in adverse event rate and completion rate of NACRT protocol between short and long NACRT. The reduction rates of CA19-9 level and SUV max were both significantly higher in patients with long NACRT than those with short NACRT (64%vs30%:P=0.009 and 51%vs23%:P< 0.0001, respectively). There was no significant difference in operation time, R0 reduction rate, Evans grade, and induction and completion rates of postoperative adjuvant chemotherapy between the two groups. However, resection rate was significantly lower in long NACRT group (96% vs 85%, P=0.041) because distant metastasis was more frequently detected before surgery. There was no significant difference in OS and RFS between R patients with short and long NACRT (P=0.871 and P=0.743, respectively). In contrast, BR-V patients with long NACRT had significantly better OS and RFS than those with short NACRT (P=0.004 and P=0.022, respectively). Conclusions: There was no significant difference between short and long NACRT in R-PDAC. Long NACRT might be more effective against BR-V PDAC.