Researchers have found evidence that two intrinsic subtypes of high-grade bladder cancer exist, and these subtypes reflect the hallmarks of breast biology.

Upon analyzing 262 bladder tumors, William Y. Kim, MD, of the University of North Carolina (UNC) Lineberger Comprehensive Cancer Center, and colleagues discovered that invasive bladder cancer can be divided into at least two molecularly and clinically distinct genetic subtypes: basal-like and luminal.

These subtypes, which have characteristics of different stages of urothelial differentiation, reflect the luminal and basal-like molecular subtypes of breast cancer and have clinically meaningful differences in outcome, the investigators wrote in a paper published online ahead of print in the Proceedings of the National Academy of Sciences.

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“It will be particularly interesting to see whether the bladder subtypes, like the breast subtypes, are useful in stratification for therapy,” Dr. Kim commented in a UNC statement describing his team’s findings.

Because no approved targeted therapies for bladder cancer currently exist, “Our hope is that the identification of these subtypes will aid in the discovery of targetable pathways that will advance bladder cancer treatment,” noted study coauthor Jeffrey S. Damrauer, a graduate student in the Curriculum of Genetics and Molecular Biology at UNC School of Medicine.

The work by Dr. Kim’s group also revealed that women had a significantly higher incidence of basal-like tumors, which are more deadly than the luminal subtype. Although more research is needed to confirm a definite link between subtype and survival rate, this finding provides a possible explanation as to why women with bladder cancer have overall poorer outcomes than do men with the disease.