Evaluation of Feasibility to Categorize Borderline Resectable Pancreatic Ductal Adenocarcinoma as T4 Tumor

Abstract

Background: Resectability of pancreatic ductal adenocarcinoma (PDAC) is defined based on the tumor extension to major vessels regardless of tumor size (TS). Usually, however, only the tumor invasion to neural plexus but not to arterial wall is confirmed pathologically. In the current AJCC/UICC staging, PDAC contacting with celiac, hepatic, or superior mesenteric artery (BR-A) ≤180° by imaging studies is categorized into T4. We investigated whether classifying clinically assessed BR-A as T4 was feasible. Methods: Patients who underwent upfront pancreatectomy for resectable PDAC (R-PDAC) or BR-A were selected. TS of ≤2 cm, >2 cm and ≤4 cm, and >4 cm was defined as TSS, TSM, and TSL, respectively. In each group, the postoperative prognosis were compared according to TS. Results: Totally 264 patients were selected. In R-PDAC group, Overall survival (OS) of the patients with TSL (n =11) was significantly worse than those with TSS (n =62) (median, 11.9 vs. 36.7 months, P = 0.003) and TSM (n =150) (median, 11.9 vs. 35.9 months, P = 0.003). In BR-A group, there was no significant difference in OS among the three groups (median, TSS (n =7) vs. TSM (n =30) vs. TSL (n =4), 14.5 vs. 24.9 vs. 8.2 months, P = 0.194). OS of BR-A group (median, 22.9 months) was comparable for that of TSL in R-PDAC group P = 0.224). Conclusion: Clinically defined BR-A was associated with poor prognosis regardless of TS, but whether they should be categorized into T4 or T3 (TS >4 cm) remains to be elucidated.