Co-occurrence of peritoneal mesothelioma and genitourinary cancers: a case series with comparative outcomes.

Objectives: Peritoneal mesothelioma (PM) shares features with genitourinary (GU) malignancies, including histologic appearance, embryologic origin and genetic predispositions. However, data on their co-occurrence are limited. The study presents a case series of PM patients with associated GU malignancies and explores outcomes following cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC). Methods: A prospectively maintained CRS-HIPEC database from a tertiary referral center (2011-2024) was reviewed. Demographics, tumor characteristics and outcomes were compared between PM patients with and without GU malignancies (including gynecologic and urologic cancers). Results: Among 237 CRS-HIPEC patients, 8/17 patients with PM were found to have another GU malignancy (median age 52.8, 62.5 % male). This included renal cell carcinoma, prostate cancer, ovarian tumors and cervical carcinoma. Most GU malignancies were diagnosed before PM (5/8), two were diagnosed post-CRS-HIPEC, and one synchronously. Three patients reported asbestos exposure; two had Conclusions: GU malignancy is common among PM patients undergoing CRS-HIPEC and could represent a higher-risk subgroup. These findings raise the hypothesis of a potential association between PM and GU malignancy. Shared origins, oncogenesis of similar cell types, environmental exposures or genetic predispositions may contribute and warrant further investigation.