Whole exome sequencing of lung adenocarcinoma and lung squamous cell carcinoma in one individual: A case report.

Multiple primary lung cancers (MPLCs) refers to two or more primary malignant tumors that occur simultaneously or successively in the lung of the same patient. Distinguishing MPLCs from intrapulmonary metastases is important for treatment strategy and prognosis. MPLCs have been considered as having different origins and clonal evolutionary processes. Whole genome sequencing (WGS) and whole exome sequencing (WES) are regarded as an effective way to identify the relationship and differentiation among MPLC nodules. Here, we report the case of a 63-year-old MPLC male patient who smoked for 40 years. Two nodules were found on chest computed tomography (CT) scan, which were further confirmed by pathology to be lung adenocarcinoma (ADC) and lung squamous cell carcinoma (SCC), respectively. WES of the two different nodules was performed, and the results showed that there was a significant genetic difference between the two nodules. Further analysis of the tumor mutation burden (TMB) of the two tumor lesions showed that the TMB of the squamous cell carcinoma was higher than that of the adenocarcinoma, indicating that the squamous cell carcinoma had a higher mutation frequency. According to the pathology and WES sequencing results, MPLCs for this case were regarded as independent of each other, with different origins and clonal evolutionary processes. In this case report, we emphasize that WES should play an important role in determining the origin of MPLC clones, and also make some explorations for the further discovery of new potential driver genes and therapeutic targets.