Background: Pulmonary carcinosarcomas (PCSs) are a heterogeneous group of non-small-cell lung carcinomas (NSCLCs) with aggressiveness and a poor prognosis. Although genetic mutations of some common lung cancer subtypes have been extensively studied, the molecular characteristics of PCSs and the existence of abnormal target genes are unknown.
Methods: In this study, the clinical and molecular characterization in 3 pulmonary sarcomatoid carcinomas (PSCs) were presented using microscope analysis and next-generation sequencing (NGS) analysis.
Results: The results revealed a carcinosarcomas subtype presenting squamous cell carcinoma and sarcoma components in all 3 cases. NGS analysis showed that 182, 316 and 230 shared mutations were detected between sarcoma and lung carcinoma from 3 patients. Two identical alterations in two genes (CSMD3  and RYR3 ) that were all shared by the two components in 3 patients. Tumor suppressor gene TP53  (5/6, 83%) showed the highest mutation frequency for driver genes here. Additionally, we focused on an LYST  mutation which was mainly present in the sarcoma components. Moreover, the clonal evolution and signature analysis confirm that lung squamous cell carcinoma and sarcoma in each PCS patient may have come from a common ancestor, and mutagenesis was possibly related to indirect effects of tobacco, age or other unknown factors.
Conclusion: Our results indicate that genetic analysis and molecular targeted therapy are necessary for the identification and treatment of these rare lung tumors. CSMD3  and LYST , as common mutation genes, may be a potential therapeutic target in PCS.
Keywords: non-small cell lung cancer, pulmonary carcinosarcoma, lung squamous cell carcinoma, sarcoma, genetic analysis