Description of the Evidence
More than 90% of bladder cancers diagnosed in the United States are pure TCCs or TCCs mixed with other histologies, primarily squamous cell carcinoma, adenocarcinoma, or both. An additional 3% to 4% are pure squamous cell carcinomas, which are approximately twice as likely to occur in women compared with men. Squamous cell carcinomas also represent a greater proportion of bladder cancers occurring in individuals who have S. haematobium infections of the bladder or who have histories of long-term indwelling urinary catheters, bladder stones, or recurrent bladder infections.[28,37,38]
Both the grade and stage at diagnosis of TCC have extremely important prognostic and therapeutic implications. Nontransitional cell histologies, however, all behave very aggressively and are less responsive to treatments other than extirpative surgery. The prognosis of patients and the choice of treatments depend on the aggressiveness and grade of the tumor.
Grade and Stage of Newly Diagnosed Bladder Cancer in an Unscreened Population
The critical nature of the histologic grade and stage of index lesions for individual prognosis and management decisions has been well recognized for many years. In a study that attempted to evaluate grade and stage in newly diagnosed bladder tumors in a population-based setting, 89% of all newly diagnosed bladder cancers in men aged 50 years and older reported to the state of Wisconsin tumor registry in calendar year 1988 had blocks and slides reviewed by a single pathologist who did not know the original diagnosis. Fifty-seven percent of specimens were grade I or II, stage Ta or T1 TCCs; 19% were grade III, stage Ta or T1 (or Tis) TCCs; and 24% were muscularis propria invading or deeper (stage T2+), almost all of which were grade III lesions or of nontransitional cell histologies. Because of Wisconsin's small population of black males aged 50 years and older (fewer than 3% of all bladder cancers occurred in nonwhites), differences in grade and stage at presentation between blacks and whites could not be determined. Similarly, this study did not look at females or at males younger than 50 years. Because of variability in histologic interpretations of bladder cancers recorded by tumor registries,[3,51] the presenting grade and stage of this malignancy in Wisconsin is known only for males aged 50 years and older.