Recent studies show an increase in neuroendocrine neoplasms, especially for the digestive tract. Previous studies suggest various risk factors that were observed for various tumor sites, e.g. a family history of cancer, tobacco and alcohol consumption as well as metabolic disorders including diabetes and obesity. A risk factor that has been little studied to date is depressive disorders, which could increase the risk of neuroendocrine neoplasms either independently or through associated risk behaviors and/or antidepressant medication. The aim of this study is to identify risk factors for neuroendocrine neoplasms based on a case-control study in order to better understand the increase of neuroendocrine neoplasms in recent decades. The study is based on a record linkage of data from the Bavarian Cancer Registry and data from the Bavarian Association of Statutory Health Insurance Accredited Physicians. While the data from the Bavarian Cancer Registry enables the identification of neuroendocrine neoplasms on the basis of histopathological findings and thus is the basis for selecting cases, the claims data from the Bavarian Association of Statutory Health Insurance Accredited Physicians provides the source population as well data on diagnoses and thus enables the investigation of risk factors.

Inclusion Criteria:

• Persons with a statutory health insurance (about 85% of the population) and at least one outpatient physician contact in Bavaria between 2021 and 2023
• Residence in Bavaria

Exclusion Criteria:

• None

Cases are defined as all persons with a malignant neuroendocrine neoplasm of the bronchopulmonary or gastroenteropancreatic system diagnosed between 2021 and 2023. Controls are defined as noncases in the source population of cases, i.e. persons with a statutory health insurance and at least one outpatient physician contact in Bavaria between 2021 and 2023, whose residence was in Bavaria. Two controls will be sampled for each case.