Superficial bladder cancer: an update on etiology, molecular development, classification, and natural history.

Superficial "non-muscle-invasive" bladder tumors represent a heterogeneous group of cancers, including those that are (1) papillary in nature and limited to the mucosa, (2) high grade and flat and confined to the epithelium, and (3) invasive into the submucosa, or lamina propria. The goal of treatment is 2-fold: (1) to reduce tumor recurrence and the subsequent need for additional therapies and the morbidity associated with these treatments and (2) to prevent tumor progression and the subsequent need for more aggressive therapy. This update reviews important contemporary concepts in the etiology, molecular mechanisms, classification, and natural history of superficial bladder cancer.