Advanced prostate cancer patients who are given drugs aimed at lowering their
testosterone production to slow the spread of tumours don't get much benefit if
the drugs are given only intermittently.
A large international study suggests that the treatment, called intermittent
androgen deprivation therapy, may actually do more harm than good, although the
numbers are vague and the regimen may temporarily reduce some side effects.
"It's not clear whether there is a benefit to intermittent therapy," said
study lead author Dr Maha Hussain, co-leader of the Prostate Cancer Program at
the University of Michigan. However, she added, "in terms of survival, it's not
At issue are patients with prostate cancer that has spread to other parts of
the body. Their prognosis is typically grim, and as part of their treatment,
many receive hormone-therapy drugs aimed at stopping the body's production of
testosterone. The treatment is either continuous or is intermittent to give
patients relief from side effects of the therapy.
The treatment, a form of castration via medication, isn't easy to tolerate.
It essentially causes a form of male menopause, Hussain said. "You end up
getting symptoms that are quite distressing, such as hot flashes, weight gain,
reduced muscle mass and impotence, and libido goes down," she said.
But it does slow the spread of the disease in about 90% of patients, Hussain
said, although at some point most patients become immune to the treatment.
What the study found
In the new study, researchers analysed the experiences of more than 1 500 men
with newly diagnosed, metastatic, hormone-sensitive prostate cancer, who were
assigned to continuous or intermittent treatment with testosterone-lowering
drugs and tracked for a median of more than nine years.
Men with a stable or declining PSA level equal to or below a cut-off of 4
ng/ml were randomly assigned to continue or to discontinue the hormone therapy.
The therapy was resumed for those in the intermittent group when the PSA climbed
to 20 ng/ml.
According to the findings, there was a 10% increase in the risk of death with
intermittent therapy. Average survival was 5.8 years for the continuous group
and 5.1 years for the intermittent group.
But the study called the findings "statistically inconclusive" for figuring
out which treatment helps men live longer. And men who took the intermittent
treatment did report better quality of life and mental health three months into
the study, but not afterward.
Hussain said continuous treatment should remain the standard if the focus is
on extending life. But those worried about side effects could still consider the
intermittent treatment, she added.
The study, which didn't examine how much each kind of treatment costs,
appears in the issue of The New England Journal of Medicine.
Dr Bruce Roth, a professor of medicine in the division of oncology at
Washington University in St. Louis, said the standard of care should probably
remain the continuous approach. Some doctors are currently experimenting with
the intermittent approach, he said, although there has been a shortage of
high-quality research to support it.
The good news, he said, is that physicians are moving closer to turning
prostate cancer into a chronic yet treatable disease, like high blood pressure
For more on prostate
cancer, try the US National Library of Medicine.
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