Recent developments in the pathophysiology of bladder cancer.

Bladder cancer is the most common cancer in the urinary tract, and transitional cell carcinoma (TCC) accounts for more than 90% of bladder tumors. Bladder cancer is responsible for 4.5% of all new malignant neoplasms and 1.9% of cancer deaths in the United States. According to 1993 estimates, 52,000 new cases of bladder cancer were diagnosed in the United States, and almost 10,000 deaths were caused by this disease. TCC is a heterogeneous neoplasm with a variable natural history and behavior pattern. Seventy to 80% of bladder cancers are manifested as early stage, superficial papillary lesions; 20% are initially diagnosed as invasive disease. Superficial tumors have a great propensity to recur, and 10-20% progress to invasion of the bladder wall. Patients with invasive tumors are at high risk for disease progression, and despite definitive therapy (frequently cystectomy), the overall 5-year mortality rate is almost 50%. Basic and clinical research have led to a better understanding of bladder cancer and are leading to new diagnostic and therapeutic strategies. This report summarizes new concepts in the pathophysiology of bladder cancer, focusing on TCC, the most common histologic type of bladder tumor.