The impact of neoadjuvant therapy in patients with left-sided resectable pancreatic cancer: an international multicenter study

To assess the association between neoadjuvant therapy and overall survival (OS) in patients with left-sided resectable pancreatic cancer (RPC) compared to upfront surgery. Left-sided pancreatic cancer is associated with worse OS compared to right-sided pancreatic cancer. Although neoadjuvant therapy is currently seen as not effective in patients with RPC, current randomized trials included mostly patients with right-sided RPC. International multicenter retrospective study including consecutive patients after left-sided pancreatic resection for pathology-proven RPC, either after neoadjuvant therapy or upfront surgery in 76 centers from 18 countries on 4 continents (2013-2019). Primary endpoint is OS from diagnosis. Time-dependent Cox regression analysis was performed to investigate the association of neoadjuvant therapy with OS, adjusting for confounders at time of diagnosis. Adjusted OS probabilities were calculated. Overall, 2,282 patients after left-sided pancreatic resection for RPC were included of whom 290 patients (13%) received neoadjuvant therapy. The most common neoadjuvant regimens were (m)FOLFIRINOX (38%) and gemcitabine-nab-paclitaxel (22%). After upfront surgery, 72% of patients received adjuvant chemotherapy, mostly a single-agent regimen (74%). Neoadjuvant therapy was associated with prolonged OS compared to upfront surgery (adjusted HR=0.69 [95%CI 0.58-0.83]) with an adjusted median OS of 53 vs. 37 months (P=0.0003) and adjusted 5-year OS rates of 47% vs. 35% (P=0.0001) compared to upfront surgery. Interaction analysis demonstrated a stronger effect of neoadjuvant therapy in patients with a larger tumor (Pinteraction=0.003) and higher serum CA19-9 (Pinteraction=0.005). In contrast, the effect of neoadjuvant therapy was not enhanced for splenic artery (Pinteraction=0.43), splenic vein (Pinteraction=0.30), retroperitoneal (Pinteraction=0.84), and multivisceral (Pinteraction=0.96) involvement. Neoadjuvant therapy in patients with left-sided RPC was associated with improved OS compared to upfront surgery. The impact of neoadjuvant therapy increased with larger tumor size and higher serum CA19-9 at diagnosis. Randomized controlled trials on neoadjuvant therapy specifically in patients with left-sided RPC are needed.