Study raises red flag over commonly used prostate cancer therapy
Helen Branswell, The Canadian Press
Published Tuesday, July 16, 2013 9:12PM EDT
Last Updated Tuesday, July 16, 2013 10:14PM EDT
TORONTO -- A new study raises a red flag about a therapy commonly used in advanced prostate cancer.
The work suggests that what's known as androgen deprivation therapy may increase a patient's risk of developing acute kidney injury.
The team behind the study says the risk they've identified doesn't outweigh the benefits of the treatment in men who have metastatic prostate cancer.
But they suggest for men who don't have advanced prostate cancer that has spread to other parts of the body, the risk-benefits formula may not be the same.
The research was led by scientists from McGill University in Montreal and is published in the Journal of the American Medical Association.
This type of study cannot prove using the treatment caused acute kidney injury; it can only say that there may be a link between using the therapy and developing the condition.
Lauren Azoulay, who is one of the authors, said the findings suggest that a sort of treatment creep that has been seen with androgen deprivation therapy in recent years should be reconsidered.
Where the treatment -- which drives down the production of hormones that fuel growth of the cancer -- used to be used only in men whose cancer had metastasized, now it is sometimes used to treat lower-grade prostate cancers or men who have had what's called a biochemical recurrence. That's when the level of PSA (short for prostate specific antigen) in a man's blood rises after the man has gone through treatment such as removing the prostate or radiation.
"For this population I think we need to be careful because the randomized controlled trials have not shown any effect of androgen deprivation therapy on survival in these patients, ... on non-metastatic patients," Azoulay said Tuesday in an interview.
The study, which was conducted using data from the United Kingdom, found what Azoulay called a "pretty strong effect" of the androgen deprivation therapy.
Among prostate cancer patients who didn't get the treatment, acute kidney injury occurred at a rate of about three cases per 1,000 people per year. Prostate cancer patients who got the treatment had an additional 4.5 cases per 1,000 people per year, bringing the rate among them to 7.5 per 1,000 people per year.
Azoulay said the nature of the U.K. databases the group mined allowed them to control for things like whether the men smoked, drank alcohol and other factors that might have increased their risk of acute kidney injury.
But Dr. Ron Wald, a nephrologist (kidney specialist) at Toronto's St. Michael's Hospital, said the study did not look for whether the men had chronic kidney diseases. Chronic kidney conditions raise one's risk of developing acute kidney injury, he said.
While he said he isn't dismissing the findings, Wald said the study results may have been affected -- raised -- by chronic kidney disease in some of the men studied.
"If you have already a background of chronic damage to your kidney, any (physical) insult you get will make you more likely than the person who doesn't have chronic kidney damage to have acute kidney injury," Wald said.
"I think that certainly caution is warranted when patients, especially those who are at high risk of acute kidney injury, get androgen deprivation therapy. I think this should raise our consciousness about the fact that the patients may be at higher risk of developing ... acute kidney injury. But ... I'm not convinced there's causality yet based on the data that are in this study."