Hormone-blocking therapy for prostate cancer does not raise the risk of fatal heart attacks as some recent studies have suggested, according to a new study from the US.
Previous research has found a link between androgen deprivation therapy (ADT) and a higher risk of myocardial infarction. Concerns were raised in 2006, when researchers reported that ADT was associated with a 44 per cent risk of diabetes, an 11 per cent increase in heart attacks, and a 16 per cent increase in sudden cardiac death.
However, the new study, conducted at the Dana-Farber/Brigham and Women’s Cancer Centre in the US, states that these fears appear unwarranted. Dr Paul Nguyen, consultant radiation oncologist at the Centre and colleagues performed a meta-analysis of randomised studies involving 4,141 prostate cancer patients.
The analysis found no difference in the rate of cardiovascular deaths in men receiving ADT compared with those who didn’t. The study couldn’t rule out that ADT might elevate the risk of fatal heart attacks in patients with a history of heart disease; the researchers have therefore said they plan to look more closely at that population.
“This message should be reassuring for the vast majority of patients considering androgen deprivation therapy,” said Dr Nguyen. “Side effects from ADT can include weight gain, insulin resistance and imbalances in blood lipids- all of which are risk factors for cardiovascular disease. But whether ADT treatment actually is a risk factor for dying of cardiovascular disease has been controversial.”
In 2010, the American Heart Association, the American Cancer Society and the American Urological Association issued a joint statement alerting doctors to the potential risk, but said they should decide what therapies to recommend.
The same year, the FDA called for labelling on hormone-blocking drugs warning of an increased risk of diabetes, heart attack, sudden cardiac death, and stroke. “In the past year, these types of warnings were turning public opinion against the therapy,” said Dr Nguyen.
“Because the risk estimates had emerged from studies that weren’t randomised controlled trials, we undertook a metaanalysis of trials that met these standards and included data on adverse side effects, as well as the efficacy of ADT.”
The authors found that cardiovascular deaths occurred in 11 per cent of the patients who underwent ADT versus 11.2 per cent in the control patients - an insignificant difference. ADT did prolong survival, as shown by the finding that allcause mortality in the treated patients was 37.7 per cent compared with 44.4 per cent in the control group.
“The remaining question is whether androgen deprivation might increase risk in men with an established history of previous heart disease, but those data weren’t available. That’s a subgroup of about five or 10 per cent of the patients,” the authors wrote in the Journal of the American Medical Association.
They added that the findings “don’t exonerate ADT from the increased risks of diabetes, insulin resistance, and weight gain. We don’t discount that, but there is benefit in ADT for patients with high-risk prostate cancers”.
Image courtesy of epSos.de, Flickr
