Taking the contraceptive pill for 10 years reduces the risk of developing ovarian cancer by 45%, according to research published online in the British Journal of Cancer.
An ongoing European study has so far involved over half a million people and is investigating the relationship between lifestyle and risk of developing cancer. The results support past findings that taking the pill for any length of time reduces the likelihood of ovarian cancer significantly.
Among women who used the pill for a year or less, the risk of developing ovarian cancer was around 28 per 100,000 per year and for those who took the pill for at least 10 years, it was 15 per 100,000 per year.
This compares to women who never used the pill, for whom the risk of developing ovarian cancer was around 38 per 100,000 per year, according to the findings.
Becoming pregnant was also shown to make developing this type of cancer less likely, with a 29% difference in number of incidences between those who have never had children and those who have had at least one full-term pregnancy. More pregnancies reduce the possibility further.
Researchers at the European Prospective Investigation of Cancer (EPIC), who conducted the research, are unclear as to the exact reasons for the findings but it is thought that changes to hormone levels influence likelihood.
Commenting on the research, Dr Richard Edmondson, a women’s cancer specialist at the University of Newcastle, said the findings “may be particularly important for women with an increased risk of ovarian cancer in their family”.
However, he noted that while taking the contraceptive pill may reduce the likelihood of developing ovarian cancer, evidence also suggests it increases the risk of breast cancer. The EPIC findings also further support this link, he said.
He added: “To put this in context, it is estimated that if 100,000 women use the pill for 10 years or more there will be 50 more breast cancers than would have otherwise occurred, but 12 fewer ovarian cancers.”
The EPIC study is funded by Cancer Research UK, the Medical Research Council and other European agencies.