The researchers suggest that aspirin reduces cancer risk by blocking key enzymes crucial for the formation of cancerous tumours, reports the Mirror.
However, the researchers insist that the finding is not reason enough for women to start popping the pill, for the high doses needed to cut cancer risk may increase the risk of gastric bleeding, as drugs such as this can damage the lining of the stomach.
Dr Emma Pennery, of Breast Cancer Care, also used women not to take the drug without consulting a doctor.
"The jury is still out. These drugs can have side effects and I would not recommend healthy young women to start taking them," she said.
The study is published in the American Journal of Epidemiology