Hormonal contraceptives linked to rare brain tumor

A new Danish study suggests that there may be a link between use of hormonal contraceptives and glioma, a rare brain tumor. The authors caution, however, that their findings do not prove cause and effect and that any risk is small.

Published in The British Journal of Clinical Pharmacology, the findings are based on analysis of data from national administrative and health registries in Denmark. For the case-control study, researchers identified women aged 15 to 49 years who had been diagnosed with histologically confirmed glioma for the first time between 2000 and 2009. These cases were each age-matched to eight population controls using risk set sampling.

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Prescription data reflecting drug exposure until 2 years before the index date were categorized by hormonal contraceptive type (combined estrogen-progestogen or progestogen) and duration of use (<1, 1 to <5, ≥5 years). Odds ratios (ORs) for an association between use of hormonal contraception and glioma were calculated using conditional logistic regression and with adjustment for potential confounders.

The researchers found that ever-use of hormonal contraceptives was associated with an OR of 1.5 (95% CI; 1.2-2.0), which increased with duration of use (OR, 1.9; 95% CI: 1.2-2.9 for use ≥5 years). The association between long-term use of a contraceptive and glioma was most pronounced with progestogen-only therapy (OR, 2.4; 95% CI:1.1-5.1), especially if that was the only type of hormonal contraception that a woman used (OR, 4.1; 95% CI: 0.8-20.8).

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