Novel Case of Isolated Peritoneal Carcinomatosis from Metastatic Prostate Cancer Carrying a Pathogenic BRCA Mutation Treated with Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy.

We present the first case of isolated peritoneal carcinomatosis (PC) from prostate cancer carrying a previously unreported pathogenic BRCA2 mutation without other organ involvement. CT showed PC with no extra-peritoneal metastases. Treatment included neoadjuvant chemotherapy, cytoreductive surgery/hyperthermic intraperitoneal chemotherapy (CRS/HIPEC), and adjuvant chemotherapy. Patient is disease-free after 30-months. Germline genetic testing showed BRCA2 c.1813dupA (p.I605Nfs*11) mutation, reported in breast and ovarian cancers. Tumor genomic testing also revealed TMPRSS2, TBX3, and TP53 mutations. Given the comparable presentation and BRCA-mutation profile to ovarian cancer, BRCA2 mutations may contribute to disease phenotypes. CRS/HIPEC may provide long-term outcomes for this unique metastatic pattern.