Dr Helen Rippon, Head of Research Management at The Prostate Cancer Charity, said:

"This large study, looking at men with prostate cancer in Sweden over ten years, is the first to specifically examine the risks of developing blood clots for men with the disease. Not surprisingly - given that cancer in general is a well-established risk factor for blood clots - the researchers have found that men with prostate cancer are at increased risk, in particular of deep vein thrombosis and clots in their lungs. From this data, the overall risk appears to be highest in men who are undergoing hormone therapy for their cancer.

"It is important to remember that the researchers have simply discovered a relationship between hormone therapy and blood clots. This does not prove that one causes the other and there may be many other factors at work that could explain this relationship.

"Men on hormone therapy should not be unduly worried as a result of this research. Hormone therapy has clear, proven clinical benefits and can keep advanced prostate cancer at bay for months or even years. The results of the study certainly do not suggest that hormone therapy should be stopped or not offered to men who would normally be expected to benefit from it in treating their cancer.

"Doctors always make treatment recommendations taking into account each man’s own medical history, and make judgements about the possible risks and benefits of this treatment on an individual basis. We urge any man on hormone therapy who is concerned that he might be at greater risk of blood clots to speak to his specialist before making any decisions about whether to continue with the treatment."