A rare family case study of multiple siblings with multiple synchronous primary lung cancers.

Abstract

e21028 Background: Familial lung cancer is rare, let alone inherited lung cancer with multiple synchronous primary lung cancer lesions. Study of inherited lung cancer may facilitate the understanding of the molecular mechanism of the tumorigenesis. Methods: We identified an extremely rare family of five siblings, four with multiple primary lung adenocarcinomas by pathological examination. DNA samples were extracted from the patient tumor tissues and libraries were prepared for next-generation sequencing (NGS) analysis using a custom 500-gene cancer panel. Results: EGFR L858R or 19DEL mutations were identified in at least one lesion in all of the four lung cancer patients. Interestingly, lung cancer patient L1 had EGFR 19DEL in one lesion and L858R in the other, lung cancer patient L2 had EGFR L858R and KRAS G12C mutation in lesion 1 and lesion 2, respectively. The mutation statuses of EGFR and KRAS were confirmed by ARMS-PCR. The mutational spectrum of the two lesions from the same patient distinguished significantly based on the 500-gene NGS panel analysis, further demonstrating the heterogeneity of cancer mutations. Taken together, these results indicate that patients L1 and L2 both had synchronous primary lung cancers. Due to the small lesions, the two lesions for patient L3 were mixed together; the concurrent EGFR L858R and 19DEL mutations in the tissue sample implicated different drivers in the two different lesions since co-occurring of these two mutations was very rare. For patient L4, EGFR L858R was identified in one lesion and uncommon mutations with low frequencies were observed in the other lesion, consistent with different driving mechanisms for the two lesions. Conclusions: To our knowledge, this is the first study identifying a family of multiple siblings with multiple synchronous primary lung cancers and using NGS to reveal the genetics. Together with germline mutation analysis, this study may shed light on the tumorigenesis of familial lung cancer.