Published in the urology journal BJUI, a large study covering nearly 128,000 cases of bladder cancer in the U.S., revealed that the disease demonstrated a 9% overall decline between the years of 1973 and 2007.
However, when examining the two main subtypes (which constitute 94% of recorded bladder tumors), researchers found that between the years of 1973 and 2007, papillary transitional cell carcinoma (PTCC) increased by 56% and non-papillary transitional cell carcinoma (NPTCC) fell by 53%.
Dr. Yawei Zhang of Yale University explains the findings, “These two subtypes of bladder cancer are normally categorized as a single disease called transitional cell carcinoma in research studies, but our findings highlight major trend differences over more than three decades.”
In their efforts to investigate trends in bladder cancer according to subtype, disease stage, and grade, researchers gathered data from the National Cancer Institute’s Surveillance and Epidemiology and End Results data for 1973 to 2007. Their analysis found different trends between non-papillary tumors, which form inside of the bladder, and papillary tumors, that grow on the outside surface of the bladder.
The findings from the investigation revealed that between 1973 and 2007, the incidence rates for bladder cancer decreased by approximately 9% from 16.7 per 100,000 to 15.2. When investigating the two main subtypes, researchers found NPTCC decreased by 53% and PTCC rose by 56%. There was also a noticeable increase in the incidence rates of grade 4 tumors, while incidence rates for grade 1, 2, and 3 tumors decreased.
Dr. Zhang concludes, “The striking differences in the trends between PTCC and NPTCC suggest that they may be two disease entities with different causes. Recent survival analysis also has shown that survival rates are substantially higher for PTCC than NPTCC. 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."