Small pancreatic ductal adenocarcinoma (≤ 2 cm): different imaging and clinicopathologic features according to extrapancreatic extension.

Abstract

Purpose: To assess features of small pancreatic ductal adenocarcinoma (s-PDA, ≤ 2 cm) according to extrapancreatic extension (EPE) and predictors for recurrence.

Methods: This retrospective study included patients diagnosed with s-PDA who underwent surgery between January 2004 and October 2021. Preoperative CT or MRI images were reviewed by two reviewers. Imaging and clinicopathologic features of s-PDA were compared according to the presence of EPE. Cox regression analyses were performed to identify predictors of recurrence.

Results: 142 patients (77 men; 64.7 ± 9.3 years) who underwent preoperative CT (n = 134) or MRI (n = 115) were included. Duct dilatation was a common imaging finding of s-PDA (CT: 75.4%, MRI: 82.6%). Of the 142 patients, 21.8% (31/142) had no EPE, while 78.2% (111/142) had EPE. Tumor size on CT (14.3 ± 8.7 mm vs. 18.2 ± 6.5 mm, p =.01) and abutment or encasement of superior mesenteric vein (13.8% vs. 40.9%, p =.02) on CT were different according to absence or presence of EPE. Recurrence was more common in s-PDA with EPE (32.3% [10/31] vs. 53.2% [59/111], p =.04). Pathologic tumor size (HR 1.103, 95% CI 1.020-1.193, p =.01), tumor size on MRI (HR 1.044, 95% CI 1.001-1.090, p =.048), and extrapancreatic neural invasion on MRI (HR 3.341, 95% CI 1.564-7.140, p =.002) were significant predictors of recurrence.

Conclusion: Even in s-PDA, tumors with EPE are larger and show higher recurrence rates. Imaging features are important for predicting presence of EPE.