The contraceptive pill gives women substantial and long-lasting protection against ovarian cancer, according to a new report by Cancer Research UK scientists in The Lancet.
The researchers found that the protection against ovarian cancer lasted for more than 30 years after women had stopped taking the Pill. They also found that the longer the Pill was used the greater the protection and that taking the Pill for 15 years halved the risk of ovarian cancer.
Researchers estimated that, in high income countries, using oral contraceptives for ten years reduces the risk of developing ovarian cancer before the age of 75 from 12 down to 8 per 1000 women, and reduces the risk of death from ovarian cancer before age 75 from 7 down to 5 per 1000 women.
The new report brings together worldwide evidence from 45 epidemiological studies of ovarian cancer in 21 countries. These include 23,257 women with ovarian cancer of whom 7,308 (31 per cent) had used oral contraceptives and 87,303 women without ovarian cancer of whom 32,717 (37 per cent) had used oral contraceptives.
Lead author Professor Valerie Beral, director of the Cancer Research UK Epidemiology Unit at Oxford University, said: "Worldwide, the Pill has already prevented 200,000 women from developing cancer of the ovary and has prevented 100,000 deaths from the disease. More than 100 million women are now taking the Pill, so the number of ovarian cancers prevented will rise over the next few decades to about 30,000 per year."