SAN ANTONIO (June 4, 2012) – New study results have just upended a decades-old prostate cancer therapy approach. The international study involving the Cancer Therapy & Research Center at The University of Texas Health Science Center at San Antonio shows that men with less advanced metastatic prostate cancer who were prescribed intermittent hormone therapy died an average of two years sooner than those on continuous therapy.
“I now treat patients very differently,” said Ian M. Thompson Jr., M.D., director of the Cancer Therapy & Research Center at the UT Health Science Center and senior author of the long-term study that he said “will change clinical care forever.”
Hormone treatments fight prostate cancer by turning off testosterone production in men’s bodies. But the side effects of those treatments include mood changes, bone loss, sexual dysfunction, hot flashes and weight gain. For those reasons, many men with less advanced metastatic cancer and their doctors have been happy to “pulse” the treatment — use it until the cancer stops growing, halt the treatment for a while, and then restart it when the cancer begins to grow again.
But when all the results came in, that group of men fared significantly worse than expected.
“The very patients you’d logically offer intermittent therapy did not do as well,” Dr. Thompson said.
“What I and so many of us who specialize in prostate cancer thought we knew, based on our experience, was simply wrong.
“This is an example of the vital importance of a well-done clinical trial.”
The results of the international study were announced yesterday at the annual meeting of the American Society of Clinical Oncology.
The quality-of-life issues that go along with hormone therapy, while occasionally a problem for some patients, are treatable, Dr. Thompson noted. If the results had been the same in both intermittent and continuous treatments, intermittent would be preferable, he said. “But it is a distant second.”
Men with more advanced metastatic disease, which generally progresses quickly and becomes hormone-resistant, had similar survival rates on both types of treatment.
The study led by SWOG, an international network of research institutions, included more than 1,500 men with hormone-sensitive metastatic prostate cancer who were randomly assigned to receive intermittent hormonal therapy or continuous hormonal therapy. Patients in the intermittent therapy group received about half as much hormonal therapy as those in the continuous therapy group.
After a median follow-up of 9.2 years, overall survival in men with minimal disease spread (meaning it did not spread beyond the spine, pelvis, and lymph nodes) was 7.1 years for those who received continuous therapy. That compares to 5.2 years for the intermittent therapy group. Among men with more extensive disease spread, overall survival was similar in both arms (4.4 years for the continuous therapy group versus 5 years for the intermittent group).
“In comparison to many current ‘breakthrough’ treatments for prostate cancer that improve survival by two to three months, this is an incredible discovery,” Dr. Thompson said.
The Cancer Therapy & Research Center (CTRC) at The University of Texas Health Science Center at San Antonio is one of the elite academic cancer centers in the country to be named a National Cancer Institute (NCI) Designated Cancer Center, and is one of only four in Texas. A leader in developing new drugs to treat cancer, the CTRC Institute for Drug Development (IDD) conducts one of the largest oncology Phase I clinical drug programs in the world, and participates in development of cancer drugs approved by the U.S. Food & Drug Administration. For more information, visit www.ctrc.net.