Urothelial cancer in white and Japanese patients in Hawaii: pathology.

The sites, growth patterns, histological grades and degrees of invasion of urothelial tumors were assessed among white and Japanese patients in Hawaii. Tissues were available from 225 white and 164 Japanese patients, representing virtually all of the urothelial tumors from these races entered into the Hawaii Tumor Registry for Oahu island between 1977 and 1986. No statistically significant interracial differences emerged from the analysis. Grade 1 papillary tumors were the most numerous types encountered, consisting of 43% of the urothelial tumors in men of both races, and 37.5% in white and 31% in Japanese women. Recently, observed increasing incidence trends of urothelial tumors among white men in the United States are associated with a synchronous decrease in mortality trends. Our analysis indicates that these diverging trends cannot be accounted for by increased numbers of noninvasive papillary tumors.