In men with prostate cancer who have had the prostate surgically removed, about a third of the time the cancer doesn’t completely go away or it comes back. In those patients, radiation therapy appears to improve long-term freedom from recurrence, but now comes strong evidence that treatment with antiandrogen drugs, or male hormone blockers—in addition to radiation—improves the rate of survival significantly, and greatly reduces the likelihood that the cancer will spread to other parts of the body.
The study followed 760 men over 12 years who had been diagnosed with prostate cancer and had their prostate removed, only to have the disease persist, as shown by increasing blood levels of prostate-specific antigen, or PSA. PSA is a standard test for prostate cancer.
Half of the men received radiation therapy alone; the other half received radiation, supplemented by 24 months of antiandrogen therapy. The 12-year survival rate for men who received radiation alone was 71.3 percent; for men who received radiation together with male hormone blockers, the rate was 76.3 percent, a significant improvement. Cancer was also far less likely to spread in the radiation plus hormone blocker group: 14.5 percent, compared with 23 percent in the radiation-only group.
These findings are likely to set a new standard for how men in this group are treated, says Dr. Zeitzer.
“The important part is survival, which is the primary goal of this study,” he explains. “The other important part is fewer patients with a metastatic diagnosis (cancer that spreads). This was a well-run study. With prostate cancer, it takes a lot of years to get the data.”
In this trial, there was one notable side effect: gynecomastia, or enlargement of the breast. But the drug that was used in the trial, high-dose bicalutamide, is not the same as the drug treatment that is more commonly employed in practice now. “Currently, there is a much lower chance of that happening,” Dr. Zeitzer says.
The results of this study will have an important long-term impact on the treatment of prostate cancer, says Serge Ginzburg, MD, FACS, (right) director of the Einstein Prostate Cancer Center. “The gold standard for any therapy is demonstrating improvement in overall survival, and the current study certainly achieves this rare metric,” says Dr. Ginzburg. “Such trials are rare, and this trial specifically is practice-changing and is likely to be incorporated in future prostate cancer management guidelines.”
One of the reasons why this study is likely to have such a far-reaching impact is simply its quality. It is what is called a randomized double-blind controlled trial. In this kind of study, some patients are given the drug or treatment under study, and others are given a placebo, or a fake treatment. The patient doesn’t know which is which, and neither do the researchers doing the study.
How do hormone blockers work? The mechanism isn’t precisely understood, says Dr. Ginzburg, but hormone blockers are thought to influence the amount of blood flow and oxygenation to the cancer. It induces, he says, a kind of “male menopause,” but men generally tolerate the treatment well.
It’s fair to describe these findings as game changing—or as the author of an editorial in the New England Journal described it to the New York Times, “a big deal.”
“I think this study proves beyond a reasonable doubt that in men with recurrent prostate cancer after surgical prostate removal, the addition of androgen deprivation therapy to radiation results in a better outcome,” Dr. Ginzburg says.
Hormone blocker therapy has been used along with radiation, but not consistently. “In this group of patients, the therapy has been used, but this (study) provides better evidence that these patients are going to have a potential benefit from it,” Dr. Zeitzer says. “At this point, it does set a standard.”
Follow Dr. Ginzburg on Twitter @sginzbu.