An aspirin a day not only helps keep cancer at bay, it may also play a life-saving role in treatment, new research suggests.

A review study involving hundreds of thousands of cancer patients found that in some cases survival chances were significantly increased by taking the painkiller.

Compared with other patients, those taking a daily low dose of aspirin were 20% to 30% more likely to be alive at any time after diagnosis.

Lead researcher Professor Peter Elwood, from the University of Cardiff, said: “The use of low-dose aspirin as a preventive in heart disease, stroke and cancer is well established but evidence is now emerging that the drug may have a valuable role as an additional treatment for cancer too.”

The Cardiff team pooled the results of 71 previous studies to highlight hidden trends. Survival rates of 120,000 cancer patients taking aspirin were compared with those of 400,000 patients who did not.

Almost half the studies involved patients with bowel cancer, while breast and prostate cancer accounted for most of the rest.

Very few of the patients suffered from serious stomach bleeding, a known potential side-effect of aspirin.

The proportion of aspirin users experiencing a serious bleed was no greater than the proportion suffering a bleed due to other causes.

Prof Elwood added: “Patients with cancer should be given the evidence now available and be helped to make their own judgment of the balance between the risks and the benefits of daily low dose.

“Evidence from further studies is urgently required, and patients should be strongly encouraged to participate in appropriate research studies.

“All patients should consult their GP before starting new medication.”