Adenocarcinoma

Adenocarcinoma cells often still try to form gland-like structures or produce mucus, which is how pathologists recognise them; an adenoma is the benign glandular counterpart, and many adenocarcinomas, notably in the colon, begin as adenomas. In lung cancer, the adenocarcinoma versus squamous distinction matters directly for treatment, because the druggable drivers (EGFR, ALK, ROS1, KRAS G12C) are found mostly in adenocarcinomas and pemetrexed is used only in non-squamous disease. Molecular testing of lung adenocarcinoma is now routine at diagnosis.