Prolonged use of hormonal contraceptives can raise the risk of brain tumours in women, says a new study.
Women in the study who used hormonal contraceptives for five years increased their risk of getting glioma, a deadly cancer that starts from the brain tissues called glia, which help support the nerve cells.
Glioma, according to the Mayo Clinic, can occur either in the brain or in spinal cord. About five in one lakh people around the world are diagnosed with the brain tumour.
Hormonal contraceptives like pill, vaginal ring and skin patches, work by altering the amount of hormones oestrogen and progestin produced in the ovaries.
They, according to Medline Plus, use manmade doses of hormone progestin or a combination of oestrogen and progestin.
These hormones, when used together, can block egg being released from the ovaries during a woman's menstrual cycle. Progestin, on the other hand, blocks sperm's entry into the uterus by creating a thick and sticky wall of mucus around the cervix.
Research in the past has linked use of these female sex hormones to certain types of cancer.
Data for the study came from the national administrative and health registries in Denmark. Dr David Gaist and colleagues from Denmark selected 317 women, aged between 15 and 49, who were diagnosed with glioma from 2000 to 2009. Each patient was compared to eight women without the brain tumour.
At the end of the study, researchers found solid evidence to show that hormonal contraceptives played a huge role in glioma.
"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," Dr Gaist said in a news release.
"Despite that, we feel our study is an important contribution and we hope that our findings will spark further research on the relationship between female hormonal agents and glioma risk," he added.
Findings of the study have been reported in the British Journal of Clinical Pharmacology. Previous studies have linked regular use of birth control pills to glaucoma, blindness and breast cancer.
