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Long-term hormone Tx increases mortality risk for men with low PSA after prostate surgery

A secondary analysis of a recent clinical trial that changed the standard of care for men with recurring prostate cancer finds long-term hormone therapy more harmful to many men and calls for rethinking treatment guidelines based on a patient's post-operative prostate specific antigen (PSA) level. Findings were presented at the 61st Annual Meeting of the American Society for Radiation Oncology (ASTRO).

The study reanalyzed data from NRG Oncology / RTOG 9601, a randomized, phase III clinical trial initially reported in 2017 that found adding two years of anti-androgen therapy to post-surgical radiation treatment for men with recurring prostate cancer increased their long-term overall survival rate. That study led to the recommendation that men with recurrent prostate cancer be treated with both radiation and long-term hormone therapy after surgery. However, a secondary analysis of this data, splitting patients into those with high and low PSA levels, found that men with low PSAs after prostate surgery gained no overall survival benefit from long-term hormone therapy and greatly increased their risk of dying from other. causes.

"What we have shown for the first time is that a patient's PSA level is a predictive biomarker," said Daniel Spratt, MD, Laurie Snow Professor of Radiation Oncology and Chair of the Genitourinary Clinical Research Program at the University of Michigan's Rogel Cancer Center. "That is, you can use a patient's PSA to better select which men should receive hormone therapy, and to predict who will benefit and who will not benefit from this treatment, and who may actually benefit from it. We found that the lower the The higher the PSA, the more likely the patient was to benefit from hormone therapy because it reduced their chances of dying from prostate cancer and resulted in improved overall survival rates. "

Dr. Spratt and his team re-examined data on 760 patients treated between 1998 and 2003 at more than 100 centers across North America whose cancer returned following surgical removal of the prostate. In the original study, patients were randomized to either post-surgical radiation therapy plus a nonsteroidal anti-androgen (bicalutamide 150 mg / day) or placebo for two years, and overall survival rates were compared. In this secondary analysis, researchers first divided patients into two groups based on their PSA levels prior to radiation: those with PSAs greater than 1.5 ng / mL (n = 118) and those with PSAs lower than 1.5 ng / mL (n = 642). , which was a stratification factor on the trial. As in the original study, they found a significant improvement in overall survival rates for patients whose PSA was higher than 1.5 ng / mL (HR 0.45 [0.25-0.81]). However, there was no overall survival benefit for men with PSA levels lower than 1.5 ng / mL (HR 0.87 [0.66-1.16]).

Long-term hormone therapy increases mortality risk for men with low PSA levels after prostate surgery. Credit: American Society for Radiation Oncology (ASTRO)

Dr. Spratt said he wanted to re-examine what happened to patients with lower PSA levels over the past two decades in how recurrent prostate cancer has been treated. At the time the RTOG 9601 trial was enrolling patients, he said, it was standard to allow the PSA to rise to high levels following radical prostatectomies before initiating radiation therapy, but that was no longer the case. "The current standard is that, after surgery, if the PSA becomes detectable at very low levels — the lower the better — we recommend giving radiation," he said.

The researchers further analyzed data for a subset of patients with PSA levels less than or equal to 0.6 ng / mL (n = 389), closer to today's standard for post-surgical radiation treatment, and found that this group was twice as likely die from causes other than cancer when hormone therapy was added, with the greatest risk of death (sHR 4.14 [1.57-10.89]) for those with the lowest PSA levels (0.2-0.3 ng / mL, n = 148). This subset of patients was also three to four times more likely to experience a combination of severe cardiac events and neurological problems (OR 3.57 [1.09-15.97], p = 0.05).

"We went into this study expecting that men with low PSAs would probably derive minimal benefit from hormone therapy, but we were surprised at the magnitude of harm that these patients experienced," said Dr. Spratt. "A lot of these side effects have been reported over the past few decades but demonstrating this in a clinical trial to this extent has never been done before."

Based on these findings, Dr. Spratt said he believes clinical guidelines for treating men with recurrent prostate cancer should be reconsidered. "For post-operative patients with low PSAs," he said, "they do very well with radiation therapy after surgery. They actually have very good long-term outcomes."

"Patients with high PSAs, over 1.5 ng / mL, should continue to receive long-term hormone therapy in addition to radiation," he said. "It improves their survival substantially. But for patients with PSAs below 0.6 ng / mL who receive post-operative radiation therapy, there needs to be a real discussion about the fact that hormone therapy has not been shown to help these men live longer. Our Studies show that long-term hormone therapy can actually hurt their survival and cause other problems. A lot of shared decision-making is needed before recommending hormone therapy to all men with low PSAs. "

Pre-salvage RT PSA predictive of hormone therapy benefit with salvage RT for recurrent prostate cancer

More information:
The abstract, "Two years of anti-androgen treatment increases other-cause mortality in men receiving early salvage radiotherapy: A secondary analysis of the NRG Oncology / RTOG 9601 randomized phase III trial," will be presented in detail at ASTRO's 61st Annual Meeting in Chicago.

Provided by
American Society for Radiation Oncology

                                                 Long-term hormone Tx increases mortality risk for men with low PSA after prostate surgery (2019, September 26)
                                                 retrieved 26 September 2019

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