Certain Factors Impact Treatment Selection in Advanced Prostate Cancer

A patient’s race, income level, geographic area of residence, and whether management is conducted by a medical oncologist or a urologist may significantly influence the type of treatment administered for metastatic castration-resistant prostate cancer, according to new study published online ahead of print in the the journal Urology Practice.  

In recent years, six treatment approaches have been shown to improve overall survival (OS) in this patient population. Investigators looked at management trends between 2010 and 2016 and examined whether patient and provider factors were associated with variations in treatment.

“We observed two substitution effects. The use of docetaxel declined as the use of oral therapies increased, suggesting that oral therapies were not only being used for patients who never would have been treated before, but oral therapies also became the preferred first-line therapy in patients who may have been otherwise offered chemotherapy,” said study investigator Megan E.V. Caram, MD, an assistant professor of internal medicine in the Division of Hematology/Oncology at the University of Michigan Ann Arbor Veterans Affairs in Ann Arbor, Michigan.

Caram and colleagues examined a claims database of commercially insured patients and identified 5,575 men who were treated with abiraterone, enzalutamide, docetaxel, cabazitaxel, sipuleucel-T, or radium-223. Those with a household income of more than $99,000 were less likely to receive an expensive oral androgen signaling inhibitor (abiraterone or enzalutamide) as first-line treatment than docetaxel compared with patients with a household income of less than $50,000 (odds ratio [OR], 0.66).

On multivariable analysis, the study also showed that, independent of other factors, patients who were black (OR, 1.43) or lived in the Pacific region vs the South Atlantic (OR, 2.68) were more likely to receive first-line oral androgen signaling inhibitors than docetaxel. In addition, men who were treated by a urologist vs a medical oncologist (OR, 16.05), or who had pre-existing heart failure (OR, 1.69), were more likely to receive first-line oral androgen signaling inhibitors over docetaxel.

“This was also not surprising since oral therapies are better tolerated than chemotherapy and have similar improvements in survival. However, we were surprised that enzalutamide, while approved more than a year after abiraterone, appeared to substitute for abiraterone rather quickly,” Caram told Cancer Network.

Since both oral therapies have demonstrated similar efficacy and tolerability in clinical trials, it was surprising that enzalutamide became the preferred therapy when providers had the chance to become comfortable with abiraterone for over a year, said Caram.

Urologists may be more likely to prescribe enzalutamide than abiraterone because of the additional monitoring parameters recommended for patients taking abiraterone, Caram theorized. “Urology offices may not have the resources to monitor liver function tests and blood pressure in between visits as is recommended for abiraterone monitoring,” she said.

One possible explanation for the paradoxical income effect on receipt of docetaxel may be the high out-of-pocket costs faced by many patients for oral medications, Caram added.

Amar Kishan, MD, an assistant professor in the Department of Radiation Oncology at the David Geffen School of Medicine at UCLA, in Los Angeles, said this is a well-done study that may be able to identify and easily ameliorate disparities in prostate cancer treatment.

“While the authors looked at the Clinformatics^TM Data Mart database specifically, the findings are likely to be reflective of broader patterns for privately insured patients,” Kishan told Cancer Network.

“This is important because metastatic castrate-resistant prostate cancer is a lethal disease for which advanced therapeutic agents are direly needed. Yet as more medications are approved in this space, it is important to ensure that there are no significant barriers or disparities to access these various treatments,” said Kishan.