However, a new study suggests that in certain cases the treatment can be delayed -- boosting the patient's quality of life.
Doctors often track blood levels of a tumor-associated protein called prostate-specific antigen (PSA) after prostate cancer surgery or radiation therapy, to gauge whether the cancer is rebounding or not.
In the new study, researchers found that it was safe to delay hormone-depleting therapy in men with rising PSA levels who did not experience symptoms or have evidence of a tumor.
One expert applauded the study. "In view of the cost and potential side effects that are associated with hormonal therapy, this is an important study that supports the notion that we don't have to jump on early hormonal therapy if PSA is showing signs of recurrence," said Dr. Ash Tewari, chair of urology at the Icahn School of Medicine at Mount Sinai, in New York City.
The study was released Wednesday ahead of the annual meeting of the American Society of Clinical Oncology (ASCO), which begins May 30 in Chicago. It will be formally presented at the meeting on June 1.
"Hormone [-depleting] therapy is one of the oldest, most common and most effective treatment approaches in prostate cancer, and these findings will influence the treatment of thousands of patients worldwide," ASCO president-elect Dr. Peter Yu said in a society news release.
"This study is also a great example of how less-aggressive treatment can sometimes offer patients optimal outcomes while sparing them from side effects that impair their quality of life," Yu added.
Natural hormones such as testosterone are known to be associated with the growth of prostate tumors. So, one common treatment, called androgen deprivation therapy, involves reducing a patient's levels of these hormones.
However, ASCO experts note that the therapy also has side effects, including sexual dysfunction, weakening bones, hot flashes, fatigue, decreased mental sharpness, depression and loss of muscle mass, among others.
But what if the therapy could be at least delayed, even if a patient's PSA levels are rising? The new study found that, in certain cases, delaying hormonal therapy in this scenario is possible.
In the study, the researchers looked at data on more than 14,000 patients. Of these, just over 2,000 saw their PSA levels begin to climb again after prostate surgery or radiation therapy. These "PSA relapse" patients were divided into two groups: those who received hormone therapy immediately and those who deferred their hormone therapy until later.
The "immediate" group received hormone-depleting therapy within three months of their PSA relapse. The "deferred" group did not receive it until they developed a tumor or symptoms. Men in the "deferred" group also received hormonal therapy if their PSA level doubled in a short period of time.
Overall, the average time from initial treatment to PSA relapse was a little more than 2 years, the researchers said. After experiencing a relapse, the men were followed for an average of almost 3.5 years.
Waiting longer to begin hormone therapy did not have a significant effect on men's long-term survival, the researchers reported. The estimated five-year survival for the "immediate" treatment group was about 85 percent, compared to just over 87 percent for the "deferred" group -- not a significant difference. The researchers concluded there was no significant benefit to starting hormone therapy right away after a PSA relapse.
Postponing treatment could, however, reduce the side effects and costs linked with hormone therapy. Waiting to begin treatment could give men two or more years of life without some of the common and distressing symptoms tied to the therapy, the researchers suggested.
"Rising PSA levels trigger a lot of anxiety, and many men want to start treatment as soon as possible," study lead author Dr. Xabier Garcia-Albeniz, a research associate at Harvard University School of Public Health in Boston, said in the ASCO news release.
"These findings suggest that there may be no need to rush to androgen deprivation therapy. If our results are confirmed in randomized trials, patients could feel more comfortable waiting until they develop symptoms or signs of cancer that are seen on a scan, before initiating [treatment]," Garcia-Albeniz explained.
However, research presented at medical meetings is typically considered preliminary until published in a peer-reviewed journal, and Tewari agreed that more research will be necessary. "Further studies are needed that can possibly guide us in selecting those who may need early therapy based on high disease burden or lowered body's immune mechanism," he said.
The U.S. National Cancer Institute has more about prostate cancer treatment.