Common prostate cancer medications may be less safe than previously thought

Men taking either of the two most common oral medications for advanced prostate cancer who had also undergone hormone therapy to treat their disease were at higher risk of serious metabolic or cardiovascular issues than patients who were only receiving hormone therapy, Michigan Medicine researchers found.

Patients taking abiraterone had 1.77 times the risk of being admitted to the emergency room or the hospital due to diabetes, hypertension or heart disease compared to those who were only on hormone therapy. Those receiving enzalutamide were at 1.22 times the risk of these issues.

Compared to patients not receiving abiraterone, those taking abiraterone were also more likely to need an outpatient visit with their physician related to at least one of these health conditions. That was not the case if the man was taking enzalutamide.

Abiraterone and enzalutamide were both found to be relatively safe in clinical trials, but concerns that the population of patients who participated in the trials was different than those in real-life settings prompted the researchers to take another look at the effects of the drugs.

For instance, this research exclusively analyzed patients with Medicare health insurance, and the majority of men studied were significantly older than those in the drugs' clinical trials.

"Patients enrolled in clinical trials tend to be highly selected and often times do not reflect the patient population in day-to-day practice," said Lillian Y. Lai, M.D., M.S., a National Institutes of Health T32 Urologic Oncology Research Fellow at Michigan Medicine and the first author of the study. "Trial participants also undergo stringent safety evaluations that some of our patients do not have access to. By studying adverse events in real-life settings, we can better understand the risks of these life-prolonging cancer treatments and help clinicians and patients make informed decisions regarding treatment."

Since metabolic and cardiovascular conditions tend to be under the purview of primary care providers, Lai and her fellow authors recommend team-based care that involves PCPs for patients with advanced prostate cancer as a way to manage these higher risks.

"With continued expansion of the indications for abiraterone and enzalutamide to earlier stages of the disease, increasing numbers of men will be receiving these therapies for longer periods of time," Lai said. "This will potentially amplify the scope of men affected and increase the magnitude of the risks of adverse events, making careful attention to management of these issues crucial."

Other authors include Mary K. Oerline, M.S.; Megan E.V. Caram, M.D., M.S.; Phoebe A. Tsao, M.D.; Samuel R. Kaufman, M.A.; Brent K. Hollenbeck, M.D., M.S.; and Vahakn B. Shahinian, M.D., M.S.

Paper cited: "Risk of metabolic and cardiovascular adverse events with abiraterone or enzalutamide among men with advanced prostate cancer," Journal of the National Cancer Institute. DOI: 10.1093/jnci/djac081