ASTRO 2019: PSA Level as Predictive Biomarker of Need for Long-Term Hormone Therapy
Posted: Friday, September 20, 2019
Long-term hormone-replacement therapy for men with recurrent prostate cancer may do more harm than good for many men, according to a secondary analysis of the NRG Oncology/RTOG 9601 randomized phase III trial. Presented at the 2019 American Society for Radiation Oncology (ASTRO) Annual Meeting (Abstract LBA1), the analysis found that men with prostate-specific antigen (PSA) levels below 1.5 ng/mL after prostate surgery gained no overall survival benefit from antiandrogen therapy, and the risk of death from other-cause mortality was increased.
“What we showed for the first time is that a patient’s PSA level is a predictive biomarker,” explained Daniel Spratt, MD, of the University of Michigan, Ann Arbor, in an ASTRO press release.
In the original study conducted from 1998 to 2003, 760 men with a tumor stage of T2 with a positive surgical margin or T3 received salvage radiation therapy plus either bicalutamide (150 mg daily) or placebo. For the analysis, Dr. Spratt and colleagues divided patients into two groups based upon their PSA levels prior to radiation: those with PSA ≤ 1.5 ng/mL (n = 642) and those with PSA > 1.5 ng/mL (n = 118).
Overall survival in men with PSA levels higher than 1.5 ng/mL was significantly improved; however, no benefit in overall survival was observed with bicalutamide in men with a PSA of up to 1.5 ng/mL. Additionally, the investigators found that men with PSA levels up to 0.6 ng/mL (n = 389) were twice as likely to die of causes other than cancer when hormone therapy was added, with the greatest risk of death for those with the lowest PSA levels (0.2–0.3 ng/mL). Severe cardiovascular events and neurologic problems were also three to four times more likely in this subset of patients.
“We went into this study expecting that men with low PSAs probably would derive minimal benefit from hormone therapy, but we were surprised at the magnitude of harm that these patients experienced,” concluded Dr. Spratt. “A lot of shared decision-making is needed before recommending hormone therapy to all men with low PSAs.”
Disclosure: The study authors’ disclosure information may be found at astro.org.