Women who take the contraceptive pill for ten years almost halve their risk of being diagnosed with ovarian cancer, according to a new study.
But experts say this must be balanced against the risk of breast cancer, which is higher in women on the pill.
For every 100,000 women on the Pill for 10 years there are 50 extra breast cancers and 12 fewer ovarian cancers, data shows.
“Women may be reassured to know that the oral contraceptive is not only an effective contraceptive but can have the added benefit of reducing their risk of ovarian cancer,” the BBC quoted Dr Richard Edmondson of the Northern Institute for Cancer Research at the University of Newcastle, as saying.
“These results are important because most women don’t know that taking the Pill or getting pregnant can help reduce their risk of ovarian cancer later on in life,” he added.
The study followed more than 300,000 women enrolled in a large European study known as EPIC (European Prospective Investigation of Cancer).
The women were taking the combined oral contraceptive pill, which contains two hormones, an oestrogen and a progestogen.
Researchers say they found evidence that taking the Pill for 10 years reduced the risk of ovarian cancer by almost half, compared with women who had used the contraceptive for a year or less.
The team also say it found evidence that having a baby reduced the risk of ovarian cancer; the more children a woman had, the bigger the protection.
The study has been published in the British Journal of Cancer.