Tumor Staging of Lung Cancer: Essential Concepts for the Radiologist.

Several important modifications have been proposed for the tumor (T) descriptor for lung cancers. New size cutoffs have been determined and there are new T descriptors for adenocarcinoma in situ, minimally invasive adenocarcinoma, and part-solid adenocarcinomas with a solid component > 0.5 cm to 3 cm (T1a, T1b, T1c). There are also recommendations for multifocal adenocarcinoma, which are classified by the lesion with the highest level T descriptor, and the number of lesions is indicated. Knowledge of these changes is important in the appropriate clinical staging of patients with lung cancer.