Taking drugs of any type often means weighing the benefits and risks. Now women on birth control may have one more risk to consider.
Danish researchers found women who use birth control pills, the patch or other hormonal contraceptives for at least five years may be at increased risk of developing a rare brain tumor, according to MedicalDaily.com.
Dr. David Gaist, a neurologist at Odense University Hospital and the University of Southern Denmark, and his colleagues found that women taking hormonal contraceptives containing estrogen, progestogen or a combination of both, showed higher rates of this rare brain tumor called glioma.
For their study, researchers decided to isolate just glioma, and one age group, premenopausal women. The team relied on Denmark's national administrative and health registries to identify women between ages 15 and 49 who had been diagnosed with glioma during the years 2000 through 2009.
In all, they identified 317 glioma cases. Of these, nearly 60 percent had used hormonal contraceptives at some point. Researchers then compared these cases to more than 2,100 glioma-free women of similar ages, about half of whom had used contraceptives.
Surprisingly, women who had used hormonal contraceptives at any point showed a 50 percent higher risk of developing the brain cancer compared to those who had not. And women who used the hormonal contraceptives for more than five years nearly doubled their risk of glioma.
In addition, Gaist and his team found that glioma risk seemed to go up the most in women who used contraception containing the hormone progestogen, rather than estrogen.
Although Gaist isn’t exactly clear about the reasons behind this, he suspects that obesity may play a role. In Denmark, regulations require doctors to not prescribe estrogen-based contraceptives to obese women. This is because estrogen can increase the risk of blood clots.
Still Gaist said, since glioma is rare, even the doubling of a rare event is still considered a small risk.
“It is important to keep this apparent increase in risk in context,” Gaist told MedicalDaily.com.