About 9400 brain tumours were diagnosed in 2011. Astrocytoma – a type of cancer called a glioma – is the most common, accounting for 34% of cases. Approximately 80% of astrocytomas are an aggressive subtype called glioblastoma multiforme. Research has suggested that long-term users of hormonal contraceptives are nearly twice as likely to develop gliomas as non-users.
Epidemiological studies reported either no link between contraceptive use and glioma or a weak protective effect in women. However, these studies enrolled only post-menopausal women or small numbers of premenopausal women. The new study examines the link in younger women.