Migraines vs. breast cancer

I’m known as the migraine queen. And with upwards of 70 such headaches each year, the name is unfortunately all too apt. But I’ve just learned of an apparent up side to my neurological disorder. Women with migraines are about 25 percent less likely to develop breast cancer than are those who don’t regularly suffer from these killer brain attacks.

Christopher Li at Seattle’s Fred Hutchinson Cancer Research Center and his colleagues recruited 4,568 breast-cancer patients between the ages of 35 and 64 for interviews on any family history of breast cancer, various lifestyle factors (such as smoking or alcohol consumption), and any diagnosis and/or prescribed treatments for migraines. All the women had been diagnosed with their invasive cancer at least 11 years ago, and lived in the metropolitan areas around Atlanta, Detroit, Los Angeles, Philadelphia or Seattle. Another 4,678 cancerfree women who were about the same ages and came from the same communities answered the same battery of questions.

The vast majority of women in each group had dodged the migraine bullet. But the share who reported having been formally diagnosed with these headaches was significantly lower among the breast cancer survivors, the researchers report in the July Cancer Epidemiology, Biomarkers & Prevention. Since any history of migraines preceded the cancer’s diagnosis, you couldn’t argue that a malignancy or its treatment was what had prevented the headaches.

The diminished cancer risk among migraineurs (as we headache sufferers are referred to in Li’s papers) held no matter how the researchers analyzed their data: on the basis of a woman’s menopausal status, race, age at onset of migraines, use of prescription migraine meds, you name it.

 An earlier examination of the link by the same team — reported last November in the same journal — found a comparable reduction in cancer risk among migraine sufferers. That far smaller study looked at not quite a third as many women, all postmenopausal.

Li’s group is not surprised by its findings, but rather gratified that their hypothesis has held up in two studies involving different populations of women. What drove these researchers to probe a seemingly protective effect of migraines was a common observation among these severe-headache sufferers that the likelihood a headache would develop seemed greatest when a woman’s estrogen production fell, such as at various times in her monthly reproductive cycle, late in pregnancy and at perimenopause. Indeed, migraines don’t typically occur until after puberty, when estrogen production climbs dramatically.

Breast cancer, by contrast, is often linked to a woman’s accumulated lifetime exposure to estrogen — through both natural production of the hormone and supplementation through birth control pills or hormone replacement therapy.  So Li’s team launched the pilot analysis it reported last November to test the idea that “Given the strong relationship between endogenous estrogen levels and breast cancer risk, migraine sufferers may experience a reduced risk of breast cancer.”

Alas, migraines are no get-out-of-jail-free card for cancer. Many migraineurs will eventually develop breast cancer. And that may reflect the fact that what triggers our headaches can be very idiosyncratic and unrelated to estrogen — such as overheating, too little sleep and/or fasting for me, versus the arrival of low-pressure fronts preceding major storms for my mom’s. And yes, these headaches tend to be hereditary (my grandmothers got them, my sister gets them, and a year ago my daughter developed her first).

A couple encouraging glimmers for the women in my family. First, there has never been a known case of breast cancer, at least going back four generations (the period for which migraine incidence is known). And the new study finds that the apparent breast cancer protection afforded by being a migraine sufferer is not compromised by taking prescription meds to limit the agonizing pain and hours of debilitating nausea associated with these headaches. Which is good, because now that I’ve found a drug that tackles my headaches fairly effectively, I would never give it up. Indeed, I literally never leave home without it.