Hormonal prostate cancer therapy tied to blood clots

Lasers are precisely pinpointed on a patient with prostate cancer at the radiation oncology center at Cape Fear Valley Medical Center June 17, 2003 in Fayetteville, North Carolina. (Chris Hondros/Getty Images)

NEW YORK (Reuters Health) - Hormone-targeted therapy for prostate cancer may raise the risk of potentially dangerous blood clots, a large U.S. study suggests.

Analyzing data on more than 154,000 older men with prostate cancer, researchers found that those who received hormonal therapy had double the rate of blood clots in the veins, arteries or lungs compared to men not on the treatment.

Of the 58,000-plus men taking hormonal therapy, 15 percent developed a blood clot over roughly four years, versus seven percent of men who did not receive get the therapy.

A clot in the blood vessels can prove fatal if it breaks loose and travels to the lungs, heart or brain.

In this study, men who developed blood clots ended up in the hospital about one-quarter of the time, the researchers report in the journal Cancer.

"By no means is this a trivial risk," said lead author Dr. Behfar Ehdaie, of Memorial-Sloan Kettering Cancer Center in New York.

For men weighing their options for prostate cancer treatment, Ehdaie said the risk of blood clots -- and other side effects -- needs to be balanced against the benefits.

Other potential side effects of hormonal therapy include weight gain, bone thinning, hot flashes and erectile dysfunction.

And for many prostate cancer patients, experts say, the benefits of hormonal therapy are not clear.

The approach is based on the fact that testosterone can fuel the growth of prostate cancer. Curbing a man's production of the hormone -- by surgical removal of the testicles or, far more often, medication -- can be helpful.

But hormonal therapy was originally given only to men with advanced prostate cancer that had spread to other sites in the body. For them, the treatment offers symptom relief that generally outweighs the risks of side effects, said Dr. Vahakn B. Shahinian, of the University of Michigan in Ann Arbor.

Hormone therapy can also improve survival when given along with radiation therapy to men with "high-risk" prostate cancer that is likely to progress. (Many prostate tumors are slow-growing and may actually never advance to the point of threatening a man's life.)

"Those are the two scenarios where there is clear-cut evidence of a benefit," said Shahinian, who wrote an editorial published with the study. "The issue comes when you look at the host of other scenarios where hormone therapy is used."

In the past couple decades, some doctors started giving hormonal therapy as a first-line therapy to men newly diagnosed with tumors that were still confined to the prostate. That's despite the fact that the benefits for those patients are not established.

In some cases, men may be in poor health, and aggressive treatment with radiation might not be wise. But the doctor and patient may feel the need to "do something," Shahinian said. So hormonal therapy is the choice.

There's also evidence that financial motives have played a part, Ehdaie noted.

By 1999, hormonal therapy was given to about half of prostate cancer patients. But studies have found that after more recent cuts in Medicare reimbursement for the therapy, fewer doctors are using it.

The bottom line, both Ehdaie and Shahinian said, is that men should thoroughly discuss the risks and benefits of different prostate cancer treatments with their doctor.

As for why hormonal therapy would promote blood clots, the mechanisms are uncertain.