Medical school researchers found that prostate cancer tumors in black men have a genetic variation that may make them more aggressive and resistant to drug treatments.

Researchers said the study, which was published Friday in the journal Nature Communications may help explain why black men are diagnosed with prostate cancer at higher rates and often have a worse prognosis than white men, according to a release.

Norman Lee, professor of pharmacology and physiology, said he started the project to study disparities in prostate cancer from a genetic perspective.

“Why is it that the African American population has a higher incidence of prostate cancer and a worse prognosis compared to those of European American descent?” Lee said in a release. “In trying to understand the genetic basis, we found that part of it may have to do with differential RNA splicing.”

Lee and his team found that tumors present in black men varied from those found in whites because the tumors generate different proteins. These proteins can make the tumors more aggressive, according to the release.

The team also found that these types of proteins can lead to drug resistance.

“We found that the protein isoforms expressed in African-Americans with prostate cancer do not always respond to targeted therapies, whereas these drugs were found to be effective in European Americans with prostate cancer and do end up killing off the cancer,” Lee said in the release. “This is a mechanism for drug resistance.”

Lee said future research should examine the impact of genetic variations in other types of cancer to gain insight into why certain cancer treatments may be ineffective.