ABSTRACT
Objective:To retrospectively analyze the relationship between patterns of local recurrence and radiotherapy target dose after adjuvant radiotherapy for the pancreatic ductal adenocarcinoma(PDAC), aiming to provide reference for exploring reasonable target and dosage.Methods:Clinical data of 138 patients with T 1-4N 0-2M 0 PDAC who underwent adjuvant radiotherapy after radical resection from April 2012 to December 2020 were analyzed retrospectively. The influencing factors of local recurrence and the correlation between local recurrence site and radiotherapy target dose were analyzed. Results:The median follow-up time was 37.2 months. The median overall survival (mOS) was 29.9 months. The 5-year OS rate was 27.4%. And the median progression-free survival (mPFS) was 13.9 months. There were 24 cases of local recurrence (17.4%), and 10 cases of local recurrence complicated with distant metastasis (7.2%). The correlation between local recurrence site and radiotherapy target dose could be evaluated in 19 patients with complete clinical data. The first local recurrence occurred near the para-aortic (Ao), the celiac axis (CA) and the superior mesenteric artery (SMA) were 8, 5 and 4 cases, respectively. The radiotherapy doses of 8 patients with local recurrence only in the PTV field were above 45 Gy. There were 8 cases of local recurrence both in and out of the PTV field, including 3 cases with dose line between 40 and 52 Gy, 2 cases with dose line between 20 and 47.5 Gy, and 3 cases with dose line between 0.5 and 52.5 Gy. There were 3 cases of local recurrence out of the PTV field, and the dose line ranged from 0 to 20 Gy.Conclusions:The local recurrence rate of PDAC after radical surgery combined with postoperative radiotherapy is low, but a small number of patients have recurrence in the high-dose range of radiation field and regional recurrence out of the field. For these patients, it may be necessary to explore a more appropriate target dose and range for adjuvant radiotherapy.