A patient with metastatic lung adenocarcinoma harboring concurrent EGFR L858R, EGFR germline T790M, and PIK3CA mutations: the challenge of interpreting results of comprehensive mutational testing in lung cancer.

Mutational testing has moved to the forefront as an integral component in the management of patients with non-small cell lung cancer (NSCLC). Currently 3 targeted therapies (erlotinib, afatinib, and crizotinib) are approved by the FDA to treat patients with specific genetic abnormalities in NSCLC. As mutational screening expands to include a greater number of genes, the results will become more difficult to interpret, particularly if mutations are found in multiple genes or genes that are not actionable at the time of testing. This case report summarizes the diagnosis and treatment of a patient with NSCLC that harbored multiple potentially targetable driver mutations. It also discusses the current NCCN Clinical Practice Guidelines in Oncology for mutational testing in NSCLC and the inherent difficulties with interpreting mutational results when multiple mutations are found in a single gene or across multiple genes.