Migraine, a common neurologic disorder that causes severe headaches, has been associated with conditions such as cardiovascular disease, dementia and cancer. A new study has revealed a possible genetic link between migraines and breast cancers.

In the latest study, published in the journal BMC, researchers found that women with any type of migraine are at an increased risk of developing breast cancer, especially estrogen receptor breast cancer – a type in which the cancer cells grow in response to the hormone estrogen.

The team also found that women who experienced migraine headaches without aura had an increased risk of ER-negative breast cancer (when the cancer cell does not have the estrogen) and had a heightened chance for overall breast cancer.

Migraines usually cause headaches on one side of the head, which may also be accompanied by nausea, vomiting and extreme sensitivity to light and sound. In some cases, people experience aura or a series of symptoms that temporarily affect vision such as blind spots, flashes of lights, and tunnel vision before the migraine attack. The patients may also suffer tingling sensations in an arm or leg, numbness in the face and difficulty speaking.

Migraines are sometimes hereditary. Certain factors such as hormones, stress, food, caffeine, weather changes, changes in sleep patterns and medications can trigger migraine headaches. Conditions such as depression, anxiety, bipolar disorder, sleep disorders and epilepsy also elevate the risk.

The disorder affects around 14-15% of the population in the world, contributing to 4.9% of global ill health measured in terms of number of years lived with disability.

Studies have shown that women are up to three times more at risk of migraine than men. Previous studies that evaluated the link between migraine and breast cancer have resulted in inconsistent findings.

The team behind the latest study gathered data from genome-wide association studies involving individuals affected by both migraines and breast cancer. The genetic data for migraine was taken from five studies that looked into more than 102,000 people with the condition, while for breast cancer, researchers used the Breast Cancer Association Consortium (BCAC) data that had about 250,000 cases.

Researchers evaluated the data using Mendelian randomization analysis that uses variation in genes to examine the causal relationship between migraine and breast cancer. They found that migraine prevalence is positively associated with breast cancer.

Researchers believe the estrogen hormone, a known trigger for migraine headaches, maybe the possible link between the two.