Neoadjuvant Chemoradiotherapy Using Moderately Hypofractionated Intensity-Modulated Radiotherapy Versus Upfront Surgery for Resectable Pancreatic Cancer: A Retrospective Cohort Study.

[BACKGROUND] The efficacy of neoadjuvant chemoradiotherapy for resectable pancreatic ductal adenocarcinoma (R-PDAC) remains unclear. This study was designed to evaluate neoadjuvant chemoradiotherapy by using intensity-modulated radiotherapy (NAC-IMRT) for R-PDAC compared with upfront surgery (UpS).

[METHODS] Among 198 patients with R-PDAC who were indicated for resection between 2013 and 2021, 130 were included in this study after excluding patients who underwent neoadjuvant chemotherapy and did not meet the NAC-IMRT criteria (Eligible set). NAC-IMRT was planned for 58 patients, and UpS was planned for 72 patients. Additionally, in 105 patients who could undergo the planned treatment (As-treated set), the surgical, pathological, and oncological outcomes were evaluated.

[RESULTS] In the Eligible set, median overall survival (OS) was 50.5 months with NAC-IMRT and 34.7 months with UpS and progression-free survival was 20.4 months with NAC-IMRT and 13.9 months with UpS. In the As-treated set, OS was longer in the NAC-IMRT group (66.7 months vs. 34.7 months, p = 0.007). On multivariate analysis, NAC-IMRT was identified as an independent factor for better OS (hazard ratio 0.617, 95% confidence interval 0.382-0.995, p = 0.047, in the Eligible set). The incidence of postoperative complications did not show a difference between the two groups, and NAC-IMRT suppressed local tumor invasion, including lymphatic, venous, perineural invasion, and lymph node metastases.

[CONCLUSIONS] NAC-IMRT may offer superior survival outcomes and manageable toxicity in R-PDAC patients compared with upfront surgery. This study supports the efficacy and safety of NAC-IMRT and recommends its consideration in R-PDAC treatment protocols.