Impact of Preoperative Tumor Size on Prognosis of Resectable and Borderline Resectable Pancreatic Ductal Adenocarcinomas.

BACKGROUND: Tumor size (TS) is a well-established prognostic factor of pancreatic ductal adenocarcinoma (PDAC). However, whether a uniform treatment strategy can be applied for all resectable PDACs (R-PDACs) and borderline resectable PDACs (BR-PDACs), regardless of TS, remains unclear. This study aimed to investigate the impact of preoperative TS on surgical outcomes of patients with R-PDACs and BR-PDACs. METHODS: Chart data from three institutions were reviewed to select patients who underwent pancreatectomy for R-PDACs and BR-PDACs between January 2006 and December 2020. The patients were divided into TSsmall and TSlarge groups according to a TS cutoff value determined for each of R- and BR-PDAC using the minimum P value approach for the risk of R1 resection. RESULTS: TS of 35 mm and 24 mm was the best cutoff value in R-PDAC and BR-PDAC, respectively. The R1 rate was higher in the TSlarge than TSsmall group, in both R- (n = 35, 37% versus n = 294, 19%; P = 0.011) and BR-PDAC (n = 89, 37% versus n = 27, 15%; P = 0.030). Overall survival was significantly better in the TSsmall than TSlarge group in R-PDAC (38.2 versus 12.1 months; P < 0.001), but comparable between the two groups in BR-DPAC (21.2 versus 22.7 months; P = 0.363). Multivariate analysis revealed TS > 35 mm as an independent predictor of worse survival in patients with R-PDAC. CONCLUSION: Larger TS was associated with a higher R1 rate and is a worse prognostic factor in patients with R-PDAC.