Urinary system.

BACKGROUND: Although site-specific cancer frequencies and incidence rates for the United States are regularly reported by the National Cancer Institute's (NCI) Surveillance, Epidemiology, and End Results (SEER) program, they have not been reported by histologic type within a specific site. This report presents data for 76,303 cancers of the urinary tract by histologic type.
METHODS: Cancer data were obtained from the SEER program. Urinary tract cancers were eligible if they were histologically confirmed, in situ or invasive, and diagnosed between 1973 and 1987. The urinary tract was divided into the following sites: kidney and renal pelvis, ureter, urinary bladder, urethra, and other urinary. Histologic types were evaluated by site, age, sex, race, incidence, and survival.
RESULTS: Of the 76,303 cancers, 72.0% were transitional cell carcinomas and 22.0% were adenocarcinomas. Adenocarcinoma was the most common histologic type in the kidney and renal pelvis (also referred to as renal cell carcinoma), whereas transitional cell carcinoma was the most common histologic type in the remainder of the urinary tract. For the more common histologic types, age-adjusted incidence rates were always higher among males than females.
CONCLUSIONS: Because adenocarcinomas represent most kidney and renal pelvis cancers and transitional cell carcinomas represent most urinary bladder cancers, these histologic types largely explain incidence and survival trends reported for these two common cancer sites. Future population-based cancer epidemiologic studies should try to focus more on specific histologic types within a cancer site to better clarify risk factors and incidence and survival trends for cancer.