A margin distance analysis of the impact of adjuvant chemoradiation on survival after pancreatoduodenectomy for pancreatic adenocarcinoma

Background: The role of adjuvant chemoradiotherapy (CRT) following pancreaticoduodenectomy (PD) for pancreatic adenocarcinoma (PDA) remains controversial. Recent data suggest that increased margin clearance (MC: distance between tumor and cut surface) is associated with improved survival after PD, but the role of adjuvant CRT in patients with known MC is undefined. We sought to delineate the impact of adjuvant CRT on survival based on MC following PD. Methods: Patients who underwent PD for PDA between 2002 and 2014 were retrospectively stratified into three groups based on MC: 0 mm, ≤1 mm, and >1 mm. The impact of CRT on survival in each MC group was determined by univariate and multivariate analysis. Results: Three hundred and ten patients with known MC were analyzed (0 mm =67, ≤1 mm =113, and >1 mm =130). Increasing MC was independently associated with improved OS (≤1 mm, HR 0.66, 95% CI 0.46–0.96, P=0.03; >1 mm, HR 0.51, 95% CI 0.35–0.75, P=0.001; compared to 0 mm). Adjuvant CRT was administered to 62 patients (20%). On margin-stratified multivariate analysis, adjuvant CRT was independently associated with increased OS in patients with ≤1 mm margins (HR 0.36; 95% CI 0.18–0.69, P=0.002) but not for 0 mm and >1 mm margins. Conclusions: This analysis suggests that the benefit of adjuvant CRT may be restricted to patients with ≤1 mm MC after PD for pancreatic cancer.