Epidemiology and etiology of urothelial (transitional cell) carcinoma of the bladder

INTRODUCTION

Bladder cancer is the most common malignancy involving the urinary system and the ninth most common malignancy worldwide [1]. Urothelial (transitional cell) carcinoma is the predominant histologic type in the United States and Western Europe, where it accounts for approximately 90 percent of bladder cancers. In other areas of the world, such as the Middle East, nonurothelial histologies are more frequent, at least in part to the prevalence of schistosomiasis.

Studies of urothelial bladder cancer have identified multiple risk factors, the most important of which are cigarette smoking and various occupational exposures. Numerous other factors have also been identified that may play an etiologic role in some cases of urothelial cancer, although interpretation of the evidence is frequently confounded by exposure to tobacco use.

The epidemiology and risk factors associated with urothelial cancer of the bladder will be reviewed here. Nonurothelial bladder cancer is discussed separately. (See "Nonurothelial bladder cancer".)

EPIDEMIOLOGY

Incidence and prevalence — In 2008, there were an estimated 386,000 new cases of bladder cancer worldwide, with bladder cancer causing approximately 150,000 deaths [2]. In the United States, there are estimated to be approximately 73,000 cases and 15,000 deaths each year due to bladder cancer [3]. In developed regions such as North America and Europe, this is predominantly urothelial carcinoma.

From 1985 to 2005 the number of bladder cancers diagnosed in the United States increased by over 50 percent, while from 1975 to 1996 the five-year survival rate for those diagnosed with bladder cancer increased from 75 to 81 percent [4,5]. Mortality rates in several western European countries have shown similar downward trends over the last two decades, but are still increasing in some eastern European countries [6].