(AP) -- A new study links hormone therapy for prostate cancer with a higher risk of death in older men who've had serious heart problems.
Hormone therapy suppresses the amount of testosterone produced, in turn causing prostate tumors to shrink or grow more slowly. The treatment, involving injections in a doctor's office, can help men with more advanced disease when used with surgery or radiation.
But the side effects are troubling: impotence, bone loss, hot flashes, memory problems, fatigue and an increased risk for diabetes and heart disease.
For the new study, appearing in Wednesday's Journal of the American Medical Association, researchers followed more than 5,000 men with prostate cancer that hadn't spread. The men, most in their 60s and 70s, were followed for an average of five years.
All the patients had brachytherapy, a type of radiation treatment, at one Illinois treatment center. Thirty percent of them also took hormone therapy for an average of four months.
Five percent of the men in the study had a history of heart failure or heart attack and 43 of those men died. Among those with heart problems, the hormone treatment was linked with a 96 percent higher risk of death after adjusting for other risk factors.
In raw numbers, of the 95 men on hormone therapy who also had a history of serious heart problems, 25 died; and of the 161 men not on hormone therapy who also had a history of heart problems, 18 died.
"Our results should heighten awareness about the potential for harm with hormonal therapy for men with pre-existing heart disease," said lead author Dr. Akash Nanda of the Harvard Radiation Oncology Program in Boston.
The study was observational, meaning the men chose their treatment with their doctors, rather than being randomly assigned to get one treatment or another. That's a less rigorous approach and means the deaths could have been caused by factors other than the hormone therapy. The small number of deaths also calls for additional research.
But the findings line up with prior studies that have found that sicker men don't benefit from hormone therapy when it's added to radiation. And hormone therapy used alone in older men has been linked to a slightly heightened risk of death.
"For those who've been following the field, this is not surprising at all," said Dr. Stephen Freedland, a Duke University prostate cancer specialist, who wasn't involved in the study.
Freedland said that although some patients benefit from hormone therapy, it's dangerous in the wrong patients. The drugs can increase insulin resistance and raise cholesterol. They increase fat, too.
He likened it to the opposite of performance-enhancing drugs some athletes have taken: "You take away the muscles and give him fat."
In some men, the hormone-blocking treatment, sometimes called chemical castration, is given as a first step before brachytherapy to reduce the size of the prostate. In the study, the drugs given were leuprolide or goserelin injections combined with oral bicalutamide or flutamide.
The treatment costs about $1,400 a month.
The study was funded by Brigham and Women's Hospital and the Dana-Farber Cancer Institute in Boston.
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