The use of histopathological subtyping in patients with ampullary cancer: a nationwide analysis

Background Recent guidelines advise to subtype adenocarcinoma at the ampulla and papilla of Vater (here: ampullary cancer) as intestinal, pancreatobiliary, and mixed, because this has consequences for both prognosis and treatment. This nationwide study aimed to investigate how often histopathological subtyping is performed in daily clinical practice in patients with ampullary cancer. Methods Pathology reports of all patients with ampullary cancer were retrieved from the Dutch nationwide pathology database (PALGA, 1991-2020). Reports were assessed for the presence and methods used for the classification of these tumors into intestinal, pancreatobiliary, and mixed subtypes. The use of immunohistochemical markers was recorded. Results Overall, 5246 patients with ampullary cancer were included. In 1030 (19.6%) patients, a distinction between intestinal, pancreatobiliary, and mixed subtypes was made. Use of subtyping increased from 3% in 1991–1993 to 37% in 2018–2020. In 274 of the 1030 (26.6%) patients, immunohistochemistry was used to make this distinction. A gradual increase in the use of various immunohistochemical markers was seen over time since 2008, with cytokeratin 7, cytokeratin 20, and CDX2 being the most common. Staining of DPC4/SMAD4 was increasingly used since 2012. Conclusion Despite recent improvements in the use of subtyping in ampullary cancer, the distinction between intestinal, pancreatobiliary, and mixed subtypes is only made in a minority of patients. Nationwide efforts are required to standardize the pathological distinction of the various subtypes of ampullary cancer.