Impact of the T and N stage in the American Joint Committee on Cancer (AJCC) 8th edition staging system for pancreatic cancer with curative resection.

Abstract

261 Background: The 8th edition of the AJCC staging system for pancreatic cancer contains several changes. T and N classification incorporate tumor size and number of positive lymph node (LN). The aim of this study was to evaluate the impact on the outcomes of the new classification for the patients who underwent curative resection and received adjuvant treatment with S-1. Methods: We retrospectively reviewed 96 patients who underwent curative resection for pancreatic ductal adenocarcinoma and received adjuvant treatment with S-1 (40, 50, or 60 mg according to body-surface area, orally administered twice a day for 28 days followed by a 14-day rest, every 6 weeks [one cycle], for up to four cycles) at our institution between January 2007 and December 2015. Inclusion criteria were as follows: PS0/1, adequate-organ functions, no critical complication, start of adjuvant therapy within 10 weeks after resection, and no active concomitant malignancy. Results: 66 patients were satisfied with these criteria. Patients characteristics were as follows: median age 67 years (range, 43-83), male 40 (61%), Pancreatoduodenectomy / Distal / Total pancreatectomy 50/14/2, combined portal vein or superior mesenteric vein resection 25 (38%), no postoperative complication 25 (38%), Well/Moderately/Poorly differentiated type 23/41/2, the median tumor size 30mm (range, 13-130), the median number of dissected LN 25 (range, 10-60), the median number of positive LN 2 (range, 0-8), and the resection margin status (R0/1) 62/4. The distribution in the 8th edition (1A/1B/2A/2B/3) was 6(9%) / 10(15%) / 5(8%) / 36(54%) / 9(14%), respectively. 2-year overall survival (OS) and relapse-free survival (RFS) were 70% and 52%. In the 8th edition staging system (1A/1B/2A/2B/3), 2-year OS and RFS were 100/90/80/66/40% and 83/70/53/49/22%, respectively. 2-year OS and RFS by T classification according to AJCC 8th edition were 100/68/56% and 90/39/56% (T1/2/3), while those by N classification were 90/66/40% and 70/49/22% (N0/1/2), respectively. Conclusions: The survival was poor with progress of the stage in the new classification. Especially at N stage, it might be suggested an association with prognosis.