Another observation of this study was the finding that wild-type TP53 and RB1 SCLC tumors were enriched for mutations in genes frequently associated with non-small cell lung cancer (NSCLC), including Kirsten rat sarcoma virus (KRAS), BRAF, Kelch-like ECH-associated protein 1 (KEAP1), and fibroblast growth factor receptor 1 (FGFR1). This evidence concerns the gene TP53 and small cell lung carcinoma.