Although a detailed trend analysis of 127,614 U.S. cases of first primary bladder cancer demonstrated a 9% overall drop in disease occurrence between 1973 and 2007, papillary transitional cell carcinoma (PTCC)—one of two main subtypes—increased by 56% over that period.
In contrast, the other main subtype, non-papillary transitional cell carcinoma (NPTCC), fell by about 53%. The results suggest that external and internal bladder tumors are two disease entities with separate causes, according to a report in BJU International (2012;109:52-56).
Lead investigator Yawei Zhang, MD, of the School of Public Health and School of Medicine at Yale University, observed that “no epidemiological studies have investigated the risk factors for these two subtypes separately. Our study suggests that future research must make clear distinctions between PTCC and NPTCC and not just treat them as subtypes of transitional cell carcinoma.”