Some Birth Control Pills Increase Brain Tumor Risk

Previous studies have shown that birth control can cause weight gain, irritability and, in more rare cases, increase the risk of blood clots. However, many women find taking it can help to regulate menstrual cycles and prevent pregnancy.

Now, recent findings published in the Journal of Clinical Pharmacology show that women on certain types of birth control may be more likely to develop brain cancer.

For the study, researchers used health data from Denmark to compare 317 who had been diagnosed with glioma, a type of brain tumor, and 2,126 who were free of disease. All participants were between the ages of 15 and 49.

Findings revealed that women who had ever used an oral contraceptive or hormone-releasing intrauterine device (IUD), or coil, were 50 percent more likely to develop brain cancer than those who had not. The risk increased to 90 percent or double for those who had used one of the contraceptives for five years or more.

Progestagen-only contraceptives were also more strongly associated with glioma, increasing the risk by nearly three-fold. The risk was also highest for the most aggressive type of brain cancer, otherwise known as gliobastoma multiforme. Furthermore, the aforementioned hormone is known to increase proliferation of high-grade glioma cells called astrocytomas. It's also thought to raise levels of growth factors, natural substances that stimulate cell growth.

"In a population of women in the reproductive age, including those who use hormonal contraceptives, you would anticipate seeing five in 100,000 people develop a glioma annually, according to the nationwide Danish Cancer Registry," said lead study author Dr. David Gaist from Odense University Hospital and the University of Southern Denmark. "While we found a statistically significant association between hormonal contraceptive use and glioma risk, a risk-benefit evaluation would still favour the use of hormonal contraceptives in eligible users."

However, researchers concluded that further studies will be needed in order to determine if progesterone-containing contraceptives actually influence brain cancer development.

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