COMMENTARY

Brachytherapy Plus EBRT for Intermediate-Risk Prostate Cancer

Gerald Chodak, MD

Disclosures

January 24, 2017

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Hello, I am Dr Gerald Chodak for Medscape. Today I want to talk about a randomized study comparing brachytherapy alone with brachytherapy combined with external-beam radiation therapy (EBRT). Prestidge and colleagues[1] reported the results of this trial in September at the American Society for Radiation Oncology (ASTRO) 2016 annual meeting.

Patients were accrued between 2003 and 2012. The investigators enrolled nearly 600 men. Participants were stratified by whether they had received androgen deprivation therapy, but it was not a mandatory requirement, which may have had some impact on the overall findings.

The patients included those with T1c to T2b disease. These intermediate-risk patients either had a prostate-specific antigen (PSA) level between 10 ng/mL and 20 ng/mL combined with a Gleason score under 7, or a Gleason score of 7 with a PSA level < 10 ng/mL.

At 5 years, investigators found no statistical difference between the groups in terms of biochemical disease-free survival. There was, however, a significant difference in long-term adverse effects of grade 3 or higher, which occurred in 12% of men in the combination therapy group compared with only 7% in the men who received brachytherapy alone. Of importance, the patients could have received either iodine or palladium as the interstitial brachytherapy implant.

What does this information tell us? First, we need to acknowledge that biochemical disease-free survival is not a firm enough outcome from which to draw the best conclusions. We really need to compare metastasis-free survival or overall survival. With longer follow-up, we will see whether or not that difference occurs in this patient population or whether it remains nonsignificant.

Until then, what do you tell patients? I believe it is important to realize that around the country, some centers have been promoting the combination therapy to intermediate-risk patients in the absence of randomized data proving that the combination clearly provides a benefit.

Another randomized trial enrolled patients with intermediate- or high-risk disease.[2] In that study, the combination of EBRT and brachytherapy appeared to result in better biochemical disease-free survival—but so far, with about 6.5 years of median follow-up, there is no difference in overall survival between brachytherapy alone and the combination. Even in that study, longer follow-up is needed.

For now, we know that men who have intermediate-risk disease do not seem to receive a significant benefit by receiving the EBRT combined with brachytherapy, at least at 5 years. But the combination does cause more side effects. Any man being presented with the option of undergoing this therapy needs to understand that there is a higher risk for side effects without any clear evidence of a higher benefit.

I look forward to your comments. Thank you.

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