Aspirin is already taken by millions of Britons with heart disease, but now it seems it may also protect men with heart trouble from prostate cancer.
A study of more than 13,000 cardiac patients showed that men taking aspirin had substantially lower levels of prostate cancer than those who did not take it.
Overall, they were 36 per cent less likely to get the disease - and among those who had been taking aspirin regularly for five or more years, the likelihood of the disease dropped by an astonishing 57 per cent.
A spokesman for the Italian team that carried out the study said: 'Our findings indicate that low-dose aspirin might be associated with a reduction of risk of prostate cancer in patients with cardio or cerebrovascular [stroke causing] diseases.
'Raising patients' awareness of its beneficial role in the prevention of prostate cancer might help improve adherence to the long-term therapy for the prevention of vascular problems.'
Aspirin, a painkiller and anti-inflammatory, is widely prescribed to people at risk of heart disease.
In patients whose blood vessels are narrowed from atherosclerosis, or 'furring' of the arteries, fatty deposits on the lining can cause a blocked artery and a heart attack.
Aspirin works by interfering with blood clotting by reducing the clumping together of platelets or clotting cells.
Studies have also suggested it may help prevent colorectal cancers in heart patients.
One theory about its anti-cancer effect is that the drug blocks cyclooxygenase or COX enzymes which are involved in the pain and inflammatory process.
COX enzymes may also be involved in the growth of new blood vessels that help cancerous tumours to grow, and that by blocking their activity, aspirin reduces the likelihood of the cancer both growing and also spreading.
Aspirin may trigger cancer cell death too.
There are nearly 50,000 new cases of prostate cancer a year and 11,000 deaths, according to Cancer Research UK.
Almost nine out of ten men diagnosed with prostate cancer survive the disease for five years or more.
The prostate study was carried out by doctors from the Italian College of General Practitioners and Primary Care and reported in the International Journal Of Cancer.