Pathological treatment response has different prognostic implications for pancreatic cancer patients treated with neoadjuvant chemotherapy or chemoradiotherapy

Background: Pathological treatment effect of resected pancreatic adenocarcinoma after neoadjuvant therapy has prognostic implications. The impact for patients who received chemotherapy alone or chemoradiotherapy is not well defined. Methods: Patients with localized pancreatic adenocarcinoma who had pancreatectomy after neoadjuvant therapy at 3 centers from 2011 to 2017 were retrospectively analyzed. The chemotherapy and chemoradiotherapy groups were evaluated separately. Results: Of 525 patients, 148 received neoadjuvant chemotherapy and 377 received chemoradiotherapy. The chemoradiotherapy group had a better treatment effect (score 0: 10%, score 1: 30%, score 2: 42%, and score 3: 18%) than the chemotherapy group (score 0: 2%, score 1: 8%, score 2: 35%, and score 3: 55%) (P <.001). Median overall survival was similar between the 2 groups (25.8 vs 26.4 months). Median overall survival for score 0/1, 2, or 3 was 72.2, 38.5, and 20.0 months in the chemotherapy group and 37.9, 24.5, and 19.0 months in the chemoradiotherapy group. Score 2 in the chemotherapy group was associated with better overall survival compared to score 3 (adjusted hazard ratio: 0.49, P =.005), whereas only combined score 0/1 reached significance over score 2 for the chemoradiotherapy group (hazard ratio: 0.63, P =.006). Conclusion: The prognostic significance of pathological treatment effect for localized pancreatic adenocarcinoma differs for patients receiving neoadjuvant chemotherapy or neoadjuvant chemoradiotherapy.