Neoadjuvant therapy duration and outcome of patients with resectable and borderline resectable pancreatic ductal adenocarcinoma (PDAC).

Abstract

436 Background: Neoadjuvant chemotherapy (NA CT) may improve surgical selection for resectable (R) PDAC, and margin negative resection in borderline resectable (BR) PDAC. Optimal duration of NA CT is unknown, as is the role of XRT with modern chemotherapy. We compared survival outcomes by duration of NA CT and NA CT + XRT. Methods: Patients with R or BR PDAC who underwent NA CT with or without XRT and followed by curative resection were included in this analysis. Data was extracted from an IRB approved pancreatic cancer database at Indiana University. Disease Free (DFS) and Overall (OS) survival were calculated from the surgery date and compared between: 1) < 3 v ≥ 3 months NA CT and 2) NA CT with/without XRT. Results: Between Summer 2008 and Summer 2018, 116 patients received NA CT with or without XRT and completed surgical resection. Median (range) age was 63 years (36, 84), stages were R=47%, BR=53%. Most patients received modified FOLFIRINOX or FOLFIRINOX (59 %), or gemcitabine/nab-paclitaxel (13%) and 24% received XRT. There were four (3 %) pathologic complete responders, all in the ≥ 3 mo NA CT + XRT group. Percent node positive was lower in NA CT + XRT versus NA CT only (median 0% vs 7.4%, p < 001), but did not differ by duration of NA CT. With a median (range) follow-up time of 13.7 mo (0.7, 83.0), median OS was 22.5 mo (19.5, 29.8) with < 3 mo NA CT versus 16.3 (12.2, 18.9) with ≥ 3 mo NA CT (p = 0.02) and was 22.6 mo (17.0, 82.9) with NA CT + XRT versus 19.5 (13.1, 22.5) in NA CT only (p = 0.03). There was no difference in DFS by duration of NA CT or XRT. Conclusions: In this study, patients who received a shorter course of chemotherapy and radiation had improved mOS when calculated from the surgery date. While this unexpected results could reflect selection bias of therapy, further analysis will account for tumor stage at diagnosis, perioperative complications and use propensity score adjustment to examine/adjust for possible treatment selection bias.