Features of T1 Pancreatic Cancer and Validation of the Eighth Edition American Joint Committee on Cancer Staging System Definition Using a Korean-Japanese Joint Cohort and the SEER Database

Abstract

Introduction: The definition of T1 pancreatic cancer was modified in the eighth edition of the American Joint Committee on Cancer staging system. The aims were to analyze the clinicopathologic features of T1 pancreatic ductal adenocarcinoma (PDAC) and investigate the validity of its definition and subcategorization. Methods: Patients confirmed to have T1 PDAC after resection between 2000 and 2019 were identified. Survival analyses and multivariate analyses were performed. The results were validated using T1 PDAC patients in the Surveillance, Epidemiology, and End Results (SEER) database. Results: Data from 1,506 patients were collected. The median survival duration of patients was 50 months, and the 5-year survival rate was 45.1%. R0 resection was unachievable in 10.0% of patients, the nodal metastasis rate was 40.0%, and recurrence occurred in 55.2%. The current T1 subcategorization was not feasible for PDAC (Fig.1), whereas subdividing into two groups with 1.0 cm cut-off was feasible. Tumors with extrapancreatic extension (72.8%) had worse outcomes than those without extrapancreatic extension (median survival 107 vs 39 months, p<0.001). Extrapancreatic extension was an independent prognostic factor whereas the current T1 subcategorization was not (Table.1). Adjuvant treatment resulted in a significant difference in survival and was also a prognostic factor. The results of this study were reproducible with data from 3,092 patients from the SEER database. Conclusion: T1 PDAC displayed aggressive behavior warranting active local and systemic treatment. The subcategorization was not feasible for PDAC, requiring better subcategorization methods. Furthermore, the role of extrapancreatic extension in the staging system should be reconsidered.Tabled 1EP02C-082VariablesUnivariate analysisHazard ratio95% CIp-valueMultivariate analysisHazard ratio95% CIp-valueAge <60 years ≥60 years1.1070.936-1.3110.235Sex Male Female0.8400.726-0.9730.0200.8460.730-0.9810.027Location Head0.0800.631 Body0.8190.687-0.9760.0250.8960.749-1.0700.225 Tail0.8190.625-1.0730.1480.9230.701-1.2160.570 Diffuse0.6410.240-1.7160.3760.8080.299-2.1800.673R status R0<0.001<0.001 R12.1091.696-2.622<0.0011.7411.394-2.173<0.001 R25.1942.577-10.465<0.0013.2631.597-6.6660.001Extrapancreatic extension No Yes1.9011.578-2.289<0.0011.4961.219-1.836<0.001T1 subcategory T1a0.0120.266 T1b1.0330.480-2.2220.9330.8230.380-1.7800.728 T1c1.8000.964-3.3610.0651.1260.591-2.1460.496N category N0<0.001<0.001 N11.6601.417-1.944<0.0011.4781.247-1.751<0.001 N22.9892.368-3.772<0.0012.5862.014-3.321<0.001Lymphovascular invasion Yes<0.0010.309 No0.7040.596-0.831<0.0010.9390.783-1.1260.498 Unknown1.0070.825-1.2300.9441.1280.909-1.4000.274Perineural invasion Yes<0.0010.092 No0.7310.623-0.858<0.0010.8890.748-1.0560.180 Unknown0.7690.514-1.1510.2020.6590.431-1.0090.055Adjuvant treatment Yes0.001<0.001 No1.2431.067-1.4480.0051.4841.266-1.739<0.001 Unknown3.0921.280-7.4700.0122.0070.822-4.8990.126 Open table in a new tab