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Bicalutamide during and after radiation shows promise for post-radical prostatectomy
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ASCO 2011 Genitourinary Cancers Symposium
ORLANDO — The addition of bicalutamide to radiation therapy significantly improved OS and freedom from progression outcomes in post-radical prostatectomy, according to findings presented here.
However, William U. Shipley, MD, of the radiation oncology department at Harvard University Medical School and Massachusetts General Hospital, said the OS results may require longer follow-up.
The radiation regimen was 64.8 Gy in 1.8 Gy fractions, and the anti-androgen regimen was 150 mg bicalutamide (Casodex, AstraZeneca) daily for 24 months during and after radiation. There were 387 patients in the combination arm and 383 patients who received radiation alone.
“The median overall survival at 7 years was 91% in the combination arm and 86% for radiation alone,” Shipley said.
“The freedom from PSA progression at 7 years was also significantly advantaged by the addition of bicalutamide,” he said, adding that the freedom from progression was 57% in the combination arm and 40% in the radiation arm (P<.0001).
“Moreover, all subgroups seem to have benefited from the drug,” Shipley said. There were significant benefits in the combination arm compared with the radiation-alone arm regarding freedom from progression. Among 226 patients with a Gleason score of less than 7, the advantage was 63% vs. 50% (P<.02); in 411 patients with a Gleason score of 7, the difference was 55% vs. 39% (P<.0006); and in 134 patients with a Gleason score of 8 to 10, the difference was 56% vs. 26% (P<.0008).
Cumulative incidence rates of metastatic prostate cancer were 7% in the combination arm and 13% in the radiation-alone arm (P<.041).
Shipley said late grade 3 to grade 4 toxicities were similar in both arms.
“Using this approach of peripheral antigen blockade before and after radiation reduced biochemical recurrence and metastatic disease,” he said. “However, the significance of benefit in overall survival, as well as analysis of risk-stratified subsets, require longer follow-up. We are going to have to wait for more events before we can report the primary endpoint of overall survival.”
The aim of the RTOG-9601 trial was to determine whether the combination of anti-androgen therapy and radiation could improve OS and cancer control outcomes in post-radical prostatectomy patients with pT2NO or pT3NO disease and elevated margins.
The trial was conducted from March 1998 to March 2003.
For more information:
- Shipley WU. #1. Presented at: 2011 Genitourinary Cancers Symposium; Feb. 15-19, 2011; Orlando, Fla.
This study was designed a long time ago, and it is close to fruition. In an average of 7 years of follow-up, we see improved survival. Every curve has shown improvement. The problem is that most people don’t realize how serious this disease was that was treated. There are relapses involved with radical prostatectomy. These men have cancer somewhere in their body, which is a huge anxiety-producing situation. Their PSA has begun to rise again.
The dogma back then was that you would radiate the prostate and hope and pray that that was the extent of the problem. The addition of the hormone improved every measure of outcome. The only negative was breast enlargement in 89% of patients, which is rather bothersome to many men.
At the Southwest Oncology Group, we have a paper coming out that involves 1,000 patients that confirms these data in spades. The combination of our results and Dr. Shipley’s results are moving toward radiation and hormones becoming the standard of care for all patients, even if their PSA is not rising.
– Nicholas Vogelzang, MD
HemOnc
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