Lung cancer is the leading cause of cancer death in the United States. Gene alterations are significant in lung tumorigenesis, with certain genes (Kristen rat sarcoma viral oncogene homolog (KRAS), epidermal growth factor receptor [EGFR], anaplastic lymphoma kinase [ALK], and B-Raf proto-oncogene, serine/threonine kinase (BRAF)) possessing alterations important in the prognosis and treatment of lung adenocarcinoma. Mutation frequencies are affected by different patient factors, such as smoking history, age, and race. Because most lung cancers occur in patients older than age of 50 years, few studies have examined molecular alterations present in these younger patients. The pathology database was searched for patients age of 50 years or younger with non-small cell lung carcinomas (NSCLCs) tested for EGFR, ALK, KRAS, and/or BRAF alterations. A total of 53 cases were identified. The mean patient age was 44.4 years old, and there were 19 men and 34 women. Of the tumors, 11.6% had ALK rearrangements, 25.5% had KRAS mutations, and 20.0% had EGFR mutations. No BRAF mutations were identified in the 28 cases tested. All but 1 (92% [12/13]) tumor with KRAS mutation were from women patients. A smoking history of greater than 5 pack-years was associated with KRAS mutations and negatively associated with EGFR mutations and ALK translocation. The frequencies of EGFR mutation and ALK translocation in the study cohort are greater than the reported frequencies among NSCLC from adults of all ages in the United States but less than the reported frequencies among NSCLC from East Asian young adults. The frequency of KRAS mutation is significantly greater than what was previously found in young Japanese patients.
Keywords: ALK; BRAF; EGFR; Fine needle aspiration; KRAS; Lung; Molecular; Non-small cell lung carcinoma; Young.
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