Men with locally advanced prostate cancer are more likely to die if their doctors shorten the time they are treated with hormone-suppressing drugs, researchers reported on Wednesday.
Prostate cancer is diagnosed in 192,000 U.S. men each year and 27,000 die. New screening tests have allowed more cases to be caught early, but the best treatment for large tumors that have spread to both lobes of the prostate has been the subject of debate.
The new study, published in Thursday's New England Journal of Medicine, followed 970 volunteers given radiation treatment combined with drugs to suppress androgen hormones such as testosterone and dihydrotestosterone.
After six months, half the men were taken off the drug; the rest continued taking it for another two and a half years.
The research team, led by Dr. Michael Bolla of Grenoble University Hospital in France, found that by every measure, those who stayed on the hormone suppression medicine longer did better than those who received the short-term treatment.
While 47 men who took the short course of drugs died of prostate cancer, only 28 in the long-term group died. And while the tumors grew or spread in 191 men who received six months of androgen-suppression therapy, only 122 men who kept getting the anti-hormone drugs had that kind of spread.
In our study, the difference in the effect of short-term and long-term androgen suppression on five-year mortality was modest, but we believe that the advantage of long-term suppression is likely to be maintained at 10 years, the team wrote in their report.
When used early in the course of the disease, androgen-deprivation therapy can improve survival, but the researchers also found that to achieve this effect therapy must be provided for at least three full years, Dr. Peter Albertsen of the University of Connecticut Health Center in Farmington wrote in a commentary.
Long-term therapy had some significant drawbacks, producing more hot flashes, lower libido and reduced sexual activity. However, both groups reported the same overall quality of life.
It is not clear whether the treatment is also best for smaller, localized prostate cancers, the kind most often diagnosed today thanks to better screening, said Albertsen.
Until further tests are done on men with that stage of cancer, he said, long-term treatment combined with radiation should be limited to patients with advanced localized disease who are receiving radiation, or to men whose disease has spread.