The effect of adjuvant chemotherapy on prognosis in patients with familial pancreatic cancer.

Abstract

691 Background: Being familial pancreatic cancer (FPC) is defined as a family in which at least two first-degree relatives have pancreatic cancer (PC). The previous study has shown that being an FPC patient is poor prognostic indicator for PC patients who undergo resection and receive adjuvant chemotherapy. However, the impact of FPC on the prognosis remains unclarified because the cohort was small and from single institutional report. Methods: This multi-center, retrospective cohort study collected the data on FPC patients who were introduced postoperative adjuvant chemotherapy without neoadjuvant chemotherapy (NAC) between January 2013 and December 2019 from 27 facilities in Japan. Among 27 facilities, data on non-familial pancreatic cancer (Non-FPC) patients serving as controls were collected from nine institutions where family history interviews were conducted in two or more departments, in order to prevent the mixing of data on FPC due to insufficient interviews. The primary endpoint was recurrence-free survival (RFS) in the study. The potential 10 confounders including preoperative and pre-adjuvant treatment induction CA19-9 levels were selected based on clinical relevance. To estimate the treatment effect of FPC, a Cox proportional hazards model was applied with adjustment for these confounders. The hazard ratio (HR) was used as the primary measure of treatment effect. Median RFS were estimated by the Kaplan-Meier method. Results: The study included 620 patients (FPC = 157; Non-FPC = 463). In the FPC group, S-1 was administered as adjuvant chemotherapy in 151 patients (96%), GEM in five patients (3%), and other in one patient (1%). The ratio of selected adjuvant chemotherapy regimens was almost the same for the Non-FPC group (P=0.665). Median CA19-9 levels before surgical resection and adjuvant chemotherapy were statistically, but not numerically different between FPC and non-FPC groups (56 vs. 54 U/mL with p = 0.005 and 13 vs. 14.1 U/mL with 0.010, respectively. Median RFS was 21.7 months in the FPC group and 25.6 months in the Non-FPC group. Among patients who received postoperative adjuvant chemotherapy without neoadjuvant chemotherapy, FPC was an independent indicator for poor RFS (Hazard ratio, 1.26; 95% Confidence interval, 1.00–1.58; P=0.049). Conclusions: The present study validated that FPC patients had a worse RFS than Non-FPC patients from multi-center, retrospective cohort study. These results suggest that different treatment strategy is needed to improve the prognosis of FPC patients.