Women who suffer from debilitating headaches are at a significantly lower risk of developing breast cancer, according to a study.
Research conducted by Fred Hutchinson Cancer Research Centre in the US shows that those with a history of migraines have a 30% lower risk of breast cancer compared to women who do not suffer such attacks.
The study, published in Cancer Epidemiology, Biomarkers & Prevention, looked at more than 3,000 women, nearly 2,000 of whom had a history of breast cancer.
Dr Christopher Li said the researchers suspected the association between breast cancer and migraines was linked to fluctuations in levels of circulating hormones. Oestrogen is known to stimulate hormonally sensitive breast cancer.
He said in late pregnancy, where oestrogen levels are high, 80% of migraine sufferers do not have the headaches.
"Migraines seem to have a hormonal component in that they occur more frequently in women than in men, and some of their known triggers are associated with hormones," he said.
He added: "While these results need to be interpreted with caution, they point to a possible new factor that may be related to breast cancer risk.
"This gives us a new avenue to explore the biology behind risk reduction. Hopefully this could help stimulate other ideas and extend what we know about the biology of the disease."