Adjuvant chemotherapy versus observation following neoadjuvant therapy and surgery for resectable stages I-II pancreatic cancer

Aim: This National Cancer Database (NCDB) analysis was performed to evaluate the outcomes of adjuvant chemotherapy (AC) versus observation for resected pancreatic adenocarcinoma treated with neoadjuvant therapy (NT). Materials and methods: The NCDB was queried for primary stages I-II cT1-3N0-1M0 resected pancreatic adenocarcinoma treated with NT (2004-2015). Baseline patient, tumour and treatment characteristics were extracted. The primary end point was overall survival (OS). With a 6-month conditional landmark, Kaplan-Meier analysis, multivariable Cox proportional hazards method and 1:1 propensity score matching was used to analyse the data. Results: A total of 1,737 eligible patients were identified, of which 1,247 underwent post-operative observation compared to 490 with AC. The overall median follow-up was 34.7 months. The addition of AC showed improved survival on the multivariate analysis (HR 0.78, p < 0.001). AC remained statistically significant for improved OS, with a median OS of 26.3 months versus 22.3 months and 2-year OS of 63.9% versus 52.9% for the observation cohort (p < 0.001). Treatment interaction analysis showed OS benefit of AC for patients with smaller tumours. Findings: Our findings suggest a survival benefit for AC compared to observation following NT and surgery for resectable pancreatic adenocarcinoma, especially in patients with smaller tumours.