In addition to mutations in the TP53 and RB1 genes and MYC amplification, genetic alterations affecting elements of the PI3K/Akt/mTOR pathway (e.g., PIK3CA, PTEN, AKT2, AKT3, MTOR, and RICTOR) are common in SCLC. The gene discussed is PIK3CA; the disease is small cell lung carcinoma.