Men who are treated for prostate cancer with hormone-targeted therapy have a higher risk of developing kidney problems, a new study suggests.
The treatment, known as androgen deprivation therapy, lowers the risk of death among men with advanced, aggressive prostate cancer.
However, researchers said it's increasingly being used to treat possible recurrences among men with less advanced disease - for whom the benefits are less clear, and the risks more worrisome.
"Our study does raise the concern that perhaps we should be more careful in prescribing androgen deprivation therapy in patients who do not have the clear indication for it," said Laurent Azoulay, who worked on the research at McGill University in Montreal.
"It's all about the balance, finding the right population for which the benefits clearly outweigh the risks," he told Reuters Health.
Hormone-targeted treatment has been linked to a higher risk of diabetes and heart disease.
For their study, Azoulay and his colleagues used UK data on 10,250 men who were diagnosed with prostate cancer between 1997 and 2008. The men were followed for an average of just over four years after their diagnosis.
During that time, 232 of them developed an acute kidney injury - a rapid drop in kidney function. The researchers compared those men to 2,721others from the study who were the same age and were not diagnosed with kidney problems.
In total, just over half of the men were taking androgen deprivation therapy.
Azoulay and his colleagues found that men taking hormone-targeted therapy were between two and three times more likely to have their kidneys stop working, once their other health conditions and medicines were taken into account.
Unlike current use, past use of androgen deprivation therapy was not tied to a higher risk of kidney injury, the study team wrote Tuesday in the Journal of the American Medical Association.
Azoulay said it's possible that changes in testosterone and estrogen levels among men on hormonal therapy might affect kidney health and how the kidneys repair themselves after an injury.
If the finding is replicated in other studies, he said doctors should consider checking men's kidney function before prescribing androgen deprivation therapy.
Dr. Vahakn Shahinian, who has studied risks of hormone treatment at the University of Michigan in Ann Arbor, called the findings "a bit of a surprise."
He told Reuters Health that it's still not clear if a link between androgen deprivation therapy and kidney injury makes sense biologically.
"It's interesting, but it certainly would require some kind of further validation… before I'd be willing to believe that this was a real effect," said Shahinian, who wasn't involved in the new study.
Still, he agreed with Azoulay that doctors should be cautious about prescribing hormone-targeted therapy.
"Where there's a clear-cut benefit, people should continue to use it and not worry about this," Shahinian said.
However, he added, "it's in those settings where there's an uncertainty about the benefits that you have to be more worried about the side effects. And I think this adds to that list."
He said that if men's doctors prescribe androgen deprivation therapy for prostate cancer, they should ask how much evidence there is for its use in their particular situation.
"They should find out if it's an area where there's been a clear-cut established benefit or if it's an area where there's a gray zone," Shahinian said.