The Outcomes of Neoadjuvant Chemoradiotherapy Using Moderately Hypofractionated Intensity Modulated Radiotherapy for Borderline Resectable Pancreatic Cancer

Abstract

Complete resection of borderline resectable pancreatic cancer (BRPC) is difficult because of its invasion to the vital vessels. Although neoadjuvant therapy is recommended for BRPC, its optimal regimens remain unclear. Neoadjuvant chemoradiotherapy using moderately hypofractionated intensity-modulated radiotherapy (NAC-MH-IMRT) has potentials to improve the treatment outcomes with shorter treatment periods. Therefore, we evaluated the outcomes for BRPC patients treated with NAC-MH-IMRT. Between February 2013 and June 2021, patients with BRPC treated with NAC-MH-IMRT at our institution were evaluated. All patients were classified as BRPC-A and BRPC-V according to NCCN guidelines. Information regarding patient status, tumor and treatment characteristics, margin-negative resection (R0) rates, histological effects assessed by Evans classification, and outcomes were obtained from the clinical records. Overall survival (OS) and progression-free survival (PFS) were calculated by the Kaplan-Meier method from the start date of any first treatment for BRPC. Toxicity was evaluated by CTCAE version 5.0. Sixty-eight patients were included in this study (Table). All patients underwent induction chemotherapy, and 67 were treated with IMRT at 42 Gy in 15 fractions with concurrent gemcitabine (for 65) or S-1 (for 2). All patients achieved completion of radiotherapy. Fifty-seven of the 68 patients (83.8%) underwent surgical exploration, and 48 patients (70.6%) had a resection. The R0 resection was achieved in 44 patients, and the R0 resection rate was 91.7% in resected patients. Therapeutic effects by Evans classification showed as below: Grade 1/2a/2b/3/4 = 6 (12.5%)/17 (35.4%)/17 (35.4%)/7 (14.6%)/1 (2.1%). Adjuvant chemotherapy was performed for 41 patients, and S-1 and gemcitabine were used for 40 and 1 patient(s), respectively. The median follow-up time and median survival time (MST) were 23.6 months and 42.7 months, and 2-year OS and PFS were 67.3% and 30.2%, respectively. Recurrence was observed in 54 patients (79.4%), and the first recurrence pattern was as follows: 7 (13.0%)/42 (77.8%)/5 (9.3%) patients had local recurrence, distant metastases, and both of them, respectively. Regarding ≥ Grade 3 gastrointestinal toxicity related NAC-MH-IMRT, grade 3 ileus was observed in 1 patient. NAC-MH-IMRT for BRPC showed preferable outcomes and acceptable toxicities with high completion rate.