Clinicopathological and Molecular Study of Peritoneal Carcinomatosis Associated with Non-Small Cell Lung Carcinoma.

To retrospectively characterize the molecular features of Non-Small Cell Lung Carcinomas (NSCLC) with peritoneal carcinomatosis (PC), clinicopathological data of 12 patients diagnosed with NSCLC and PC between 2007 and 2016 were collected. Immunohistochemistry and Next Generation Sequencing (NGS) were performed on cases with available material. PC was the initial presentation of NSCLC in 17% of the cases. Overall, patients with PC displayed a poor median survival of 12 weeks. Histology was adenocarcinoma in 11 cases. 37.5% of cases showed PD-L1 immunostaining positivity (50% cut-off). ALK and ROS1 immunostainings were negative. Using NGS, we identified 17 molecular alterations in 9 genes (TP53, KRAS, STK11, BRAF, EGFR, DDR2, ERBB4, SMAD4, CTNNB1) in 88.9% of adenocarcinomas. To the best of our knowledge, 5 of these variants are not referenced in the literature. In conclusion, PC might be the initial presentation of NSCLC. Molecular profiling of our cases did not find any effective targetable alteration, except from high PD-L1 expression.