Hormone therapy for prostate cancer raises heart risk
Men who are given hormone therapy for advanced prostate cancer face an increased risk of heart problems, UK scientists have found.
Researchers at King's College London, who were part-funded by Cancer Research UK, discovered that while hormone therapy is associated with heart-related side-effects, certain types are less harmful than others.
The team carried out a three-year study involving 30,642 Swedish men with prostate cancer that had partially or fully spread, all of whom had received hormone therapy between 1997 and 2006.
Three types of hormone therapy were used - removal of the testicles to eliminate testosterone production; injections of gonadotropin releasing hormone agonists to reduce the production of testosterone; and anti-androgen pills, which block testosterone from encouraging prostate cells to grow.
The researchers found that prostate cancer patients who were treated with any kind of hormone therapy had a 24 per cent increased risk of a non-fatal heart attack; a 19 per cent increased risk of arrhythmia (i.e. an abnormal heart beat); a 31 per cent increased risk of coronary heart disease; and a 26 per cent increased risk of heart failure.
They also faced an increased risk of fatal heart attack (28 per cent), dying from heart disease (21 per cent), dying from heart failure (26 per cent) and fatal arrhythmia (five per cent).
Researchers told the European cancer congress ECCO 15 - ESMO 34 that doctors should consider these side-effects when prescribing hormone therapy for prostate cancer.
Lead researcher Mieke Van Hemelrijck, a cancer epidemiologist at King's College London, commented: "We estimate that compared with what's normal in the general population, about ten extra ischaemic heart disease events a year will appear for every 1,000 prostate cancer patients treated with such drugs."
However, Ms Van Hemelrijck noted that different types of hormone therapy were found to raise the risk of heart problems to varying degrees.
She revealed: "We found that drugs which block testosterone from binding to the prostate cells were associated with the least heart risk, while those that reduce the production of testosterone were associated with a higher risk. This may have implications for treatment choice."
The team found that while men taking anti-androgen pills - which block testosterone from binding to prostate cells - still faced a slightly elevated risk of ischaemic heart disease, heart attack and heart failure, there was "no increase in risk of death from heart disease in this group".
"The finding that anti-androgens carry the least heart risk supports the view that circulating testosterone may protect the heart," Ms Van Hemelrijck added.
Professor Malcolm Mason, Cancer Research UK's prostate cancer expert, commented: "This is an extremely important study. It confirms that hormone therapies for prostate cancer do increase the risks of heart disease, something which has been suggested in other studies.
"But it also suggests for the first time that one form of hormone therapy - anti-androgen tablets - might carry less risk than other forms of hormone therapy such as injections.
"This will be an important consideration for those men at risk of heart disease in choosing hormone therapy, bearing in mind that for some patients anti-androgens may be less effective than injections in controlling the cancer."