Small doses of aspirin may block the growth and spread of the most virulent strains of breast cancer, research has revealed.
Cancer campaigners cautiously welcomed the announcement – but warned the research is in its early stages.
US scientists said laboratory tests and tests on mice showed aspirin directly and indirectly suppressed the proliferation of breast cancer strains, including the so-called "triple negative" cancer which is immune to most treatments and leaves women with few options to fight it.
Aspirin also boosted the effect of tamoxifen, a widely used treatment for the more common form of the disease, a study presented to the American Society for Biochemistry and Molecular Biology showed yesterday.
Eluned Hughes, of charity, Breakthrough Breast Cancer, urged caution over the "incredibly early stage research" which is yet to be tested on any of the 39,000 patients diagnosed in the UK each year. But she added: "It could be promising for the future. We'll watch this closely to see how it progresses."