Cancer risk in patients with migraine: A population-based cohort study in Denmark.

For most cancer groups, our results did not support an association with migraine. The exceptions were an increased risk for cancers of neurological origin and a decreased risk for gastrointestinal cancers. These findings may reflect a true difference in risk among individuals with migraine, or more plausibly they reflect other forces, such as differences in medication use, detection bias and reverse causation, or shared risk factors.