(RxWiki News) Previously, researchers thought that the causes of bladder cancers were similar, but it appears that's not the case.
While the overall rate of bladder cancer has been decreasing over the last thirty years, one subtype increased by 56 percent. This realization has raised some major questions about current theories on cause and effect.
"Quit smoking to reduce your risk of bladder cancer."
During an analysis of data collected by the National Cancer Institute, a group from Yale University found that papillary transitional cell carcinoma became more common from 1973-2007. Given this disparity, researchers urge distinction between the two distinct types of transitional cell bladder cancer, papillary and non-papillary (PTCC & NPTCC).
"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" says lead author Yawei Zhang M.D., Ph.D., from the School of Public Health and School of Medicine at Yale University.
In the study, data from 128,000 American patients with bladder cancer was examined for trends. Cigarette smoking and on-the-job exposure to certain chemicals was thought to cause the majority of bladder cancer, and the declining rates supported that.
Now that it has been identified, further research needs to be done to explore the unusual rise in papillary transitional cell carcinoma.
Dr. Zhang concluded, "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."
The majority of cases were in white males. According to the American Cancer Society, bladder cancer represents seven percent of new cancer cases, making it the fourth most commonly diagnosed cancer in 2009 for men in North America.
The study was published in British Journal of Urology International (BJUI). No conflicts of interest were disclosed by the study's authors.