Tumour origin, diagnostic accuracy and histopathological evaluation in patients with periampullary cancer: nationwide cohort study

BACKGROUND: The prevalence of different periampullary cancers (pancreatic ductal adenocarcinoma, distal cholangiocarcinoma, ampullary cancer and duodenal cancer) is heterogeneous in the literature. During the 2010s, a standardized histopathological protocol for pancreatoduodenectomy specimens based on axial slicing was adopted in Sweden. The present study sought to provide information about periampullary cancers with regard to tumour types in curative and noncurative settings, preoperative diagnostic accuracy and the impact of a standardized evaluation of the surgical specimen on diagnosis, R status and lymph node assessment. METHODS: Data from patients diagnosed with periampullary cancer from 2010 to 2019 were retrieved from the Swedish National Registry for Pancreatic and Periampullary Cancer. RESULTS: Among non-curative patients, 3704 (83.6 per cent) were diagnosed with pancreatic ductal adenocarcinoma. Among patients treated with pancreatoduodenectomy, diagnosis was pancreatic ductal adenocarcinoma in 1380 (50.0 per cent), distal cholangiocarcinoma in 284 (10.3 per cent), ampullary cancer in 376 (13.6 per cent), duodenal cancer in 160 (5.8 per cent) and other diagnoses in 560 (20.3 per cent) patients. The preoperative diagnosis corresponded to the postoperative in 1177 (67.5 per cent) patients for pancreatic ductal adenocarcinoma, 162 (37.4 per cent) patients for distal cholangiocarcinoma, 220 (61.3 per cent) patients for ampullary cancer and 120 (53.6 per cent) patients for duodenal cancer. A higher rate of pancreatic ductal adenocarcinoma was seen in surgical specimens who underwent standardized evaluation, from 56.8 per cent to 64.3 per cent (P = 0.003). After standardization, higher rates of R1 resection (31.7 per cent versus 44.6 per cent, P < 0.001) and N1 stage (62.1 per cent versus 77.0 per cent, P < 0.001) were found. CONCLUSION: The proportion of pancreatic ductal adenocarcinoma was higher in patients in a non-curative setting compared with patients who underwent surgery. The rate of misdiagnosis for periampullary cancers was confirmed to be high. Thus, it should be taken into account when preoperative oncological treatment is considered. Standardized evaluation of the surgical specimen has increased pancreatic ductal adenocarcinoma, R1 and N1 rates.