Associations of selected atypical non-neuroendocrine cancers with multiple endocrine neoplasia type 1

Context: Multiple endocrine neoplasia type 1 (MEN1) is a hereditary tumor predisposing syndrome, characterized by typical neuroendocrine tumors in parathyroid, pituitary, and endocrine pancreas tissues ("3P"). MEN1 is also associated with non-neuroendocrine cancers, which are less studied. Objective: To assess the prevalence of certain non-neuroendocrine cancers associated with MEN1 in Finnish patients and compare the findings with a local control population. Design: Retrospective registry-based cohort study. Methods: = 1 045 520 males, average follow-up of 73 patient-years). Data were analyzed using descriptive statistics, survival curves, and Cox regression models. Results: Seven women with MEN1 (11.5%) had breast cancer (BC), 7 (6.2%) with papillary thyroid carcinoma (PTC), and 5 (4.4%) with renal cancers (RC). The mean age at BC diagnosis was 49 years compared to 60 in the general Finnish population. The hazard ratio (HR) for BC in female MEN1 patients was 3.79 (95% CI: 1.66-8.60) compared to controls. Pathogenic variants in established BC risk genes were not present in our MEN1 patients. The HR for PTC and RC were 9.37 (3.59-24.41) and 7.80 (2.74-22.25), respectively. Conclusion: This study demonstrates a significantly increased prevalence of BC, PTC, and RC in MEN1 patients compared to the Finnish general population. The findings support earlier BC screening in women with MEN1 and highlight the need for further research into non-neuroendocrine cancer risks in these patients.