Clinical Characteristics of Resected Acinar Cell Carcinoma of the Pancreas: A Korean Multi-Institutional Study

SIMPLE SUMMARY: Pancreatic acinar cell carcinoma accounts for less than 1% of primary pancreatic neoplasms. Because of its rarity, its characteristics and clinical outcomes remain unclear. Treatment strategies for pancreatic acinar cell carcinoma have relied on those of pancreatic ductal adenocarcinoma. In previous studies, it has been difficult to identify its characteristics due to the lack of cohort numbers in single institutional studies with detailed data and the lack of detailed data in large cohort multi-institutional studies. This retrospective multicenter cohort used a database founded in 2015 by the Korean Association of Hepato-Biliary Pancreatic Surgery. This database has collected nationwide patient data with details. In the present study, we aimed to better understand clinical outcomes of resected pancreatic acinar cell carcinoma and to lay the groundwork for establishing proper treatment strategies. ABSTRACT: Given the rare incidence of pancreatic acinar cell carcinoma (PACC), its post-resection clinical outcomes remain unclear. Treatment strategies for PACC have relied on those of pancreatic ductal adenocarcinoma (PDAC). The present study retrospectively investigated clinicopathologic characteristics of resected PACC registered in the Korea Tumor Registry System Biliary Pancreas database. Among 59 patients with a mean age of 59.2 years and a male predominance (83.1%), 43, 5, 7, and 4 had pure PACC, ductal differentiations, mixed neuroendocrine carcinomas, and intraductal and papillary variants, respectively. The mean tumor size was 4.6 cm, consisting of eight at T1, 26 at T2, and 25 at T3 stages. Metastasis to regional lymph node was identified in 15 (25.4%) patients. Thirty-one (52.5%) patients received adjuvant therapy. Five-year survival rate was 57.4%. The median survival was 78.8 months. In survival comparison according to the stage with AJCC system, N stage (lymph node metastasis), but not T stage, showed significant differences (p = 0.027). Resected PACC appeared to have clinical outcomes distinct from those of PDAC in this nationwide study. Therefore, large-scale multinational studies are needed to overcome the rarity of PACC and to establish an appropriate treatment strategies and staging system.