Team Finds 12 Markers for Radiation-Associated Erectile Dysfunction

Barry Rosenstein, PhD

A research team led by Albert Einstein College of Medicine of Yeshiva University and Mount Sinai School of Medicine in New York City, has discovered 12 genetic markers associated with the development of erectile dysfunction (ED) in prostate cancer patients treated with radiation. The findings were published online in the International Journal of Radiation Oncology — Biology – Physics.

"Thankfully, current treatments for prostate cancer offer excellent rates of long-term survival, so patients and their physicians have a choice about which treatment path to take," said Barry Rosenstein, PhD, professor of radiation oncology at Mount Sinai School of Medicine. "However, the risk of developing erectile dysfunction after radiation treatment is highly variable, suggesting there may be a genetic component to determining that risk. Our study confirms that specific markers make certain patients more susceptible to this side effect."

The Genome-Wide Association Study was conducted in two-parts: first, to discover the candidate genetic markers of side-effect risk; and second, to confirm which of those markers are replicated in a second group of patients. In the first group that included 132 prostate cancer patients who developed ED after radiotherapy and 103 men similarly treated who did not, researchers found a set of genetic markers associated with ED. In the second part of the study, examining 128 patients who developed ED after radiotherapy and 102 who did not, researchers confirmed that 12 single nucleotide polymorphisms (SNPs) were associated with the condition.

Patients in the study cohort were given one of three treatments: brachytherapy; brachytherapy plus external-beam radiation; or externalbeam radiation alone. They were followed for an average of nearly 4 years to determine level of sexual function after treatment. Interestingly, the 12 SNPs identified in this study were located near genes that seem to be related to erectile function, rather than related to radiation response. The researchers conclude that these SNPs may affect genes that sensitize a patient to developing ED when exposed to radiation during therapy.

Harry Ostrer, MD

The authors indicate that examination of a large, independent cohort of similarly treated patients will be necessary to definitively determine which SNPs to include as part of a clinically useful predictive test to identify which men are at greatest risk for developing ED following prostate cancer radiotherapy.

"Prostate cancer screening and treatment are undergoing major shifts," said Harry Ostrer, MD, director of genetic and genomic testing for the division of clinical pathology at Montefiore Medical Center and co-principal investigator of the study. "This is part of our ongoing effort to identify men at highest risk for disease, identify the aggressive tumors that would be responsive to therapy, and to improve quality of life for men with indolent prostate cancers who might benefit from active surveillance, rather than therapy."