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).

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.

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.

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.