The Association Between Neoadjuvant Therapy and Pathological Outcomes in Pancreatic Cancer Patients After Resection: Prognostic Significance of Microscopic Venous Invasion

BackgroundThe impact of neoadjuvant therapy (NAT) on pathological outcomes, including microscopic venous invasion (MVI), remains unclear in pancreatic cancer.MethodsA total of 456 patients who underwent pancreatectomy for resectable and borderline resectable pancreatic cancer between July 2012 and February 2020 were retrospectively reviewed. Patients were divided into two groups: patients with NAT (n = 120, 26%) and those without NAT (n = 336, 74%). Clinicopathological factors, survival outcomes and recurrence patterns were analyzed.ResultsRegarding pathological findings, the proportion of MVI was significantly lower in patients with NAT than in those without NAT (43% vs 62%, P = 0.001). The 5-year survival rate in patients with NAT was significantly better than that in those without NAT (54% vs 45%, P = 0.030). A multivariate analysis showed that MVI was an independent prognostic factor for the overall survival (OS) (hazard ratio 2.86, P = 0.003) in patients who underwent NAT. MVI was an independent risk factor for liver recurrence (odds ratio [OR] 2.38, P = 0.016) and multiple-site recurrence (OR 1.92, P = 0.027) according to a multivariate analysis. The OS in patients with liver recurrence was significantly worse than that in patients with other recurrence patterns (vs lymph node, P = 0.047; vs local, P < 0.001; vs lung, P < 0.001). The absence of NAT was a significant risk factor for MVI (OR 1.93, P = 0.007).ConclusionMVI was a crucial prognostic factor associated with liver and multiple-site recurrence in pancreatic cancer patients with NAT. MVI may be reduced by NAT, which may contribute to the improvement of survival in pancreatic cancer patients.