Understanding lung cancer molecular subtypes

• Histological examination of a tissue biopsy is required to differentiate between different lung cancer histiotypes. • In non-small-cell lung cancer, judicious use of a limited immunohistochemistry panel is recommended to differentiate between squamous cell and adenocarcinoma, and maximize tumor material for molecular analyses. • Clinical selection criteria should not be used to select patients for tumor genotyping. • All patients with advanced nonsquamous non-small-cell lung cancer should undergo tumor genotyping for the presence of EGFR-activating mutations and if found, receive first-line treatment with an EGFR tyrosine kinase inhibitor. • Rebiopsy of a progressive site is recommended for patients with acquired EGFR kinaseinhibitor resistance, to exclude small cell (or high-grade neuroendocrine) carcinoma change and identify additional molecular aberrations for trial therapy. • All advanced nonsquamous (and selected squamous cell carcinomas) should undergo ALK testing, and if positive receive crizotinib within its licensed indication.