British researchers have found that taking the birth control pill lowers women?s chance of getting ovarian cancer. Women taking the pill for 15 years cut their chances of getting this often fatal form of cancer in half.

The information comes from a series of 45 studies conducted worldwide of over 120,000 women, some with ovarian cancer and some without, both on and off the pill. The studies showed that women who took oral contraceptives for a decade were less likely to develop ovarian cancer. Without the pill, about 12 women per 1,000 are expected to get ovarian cancer before age 75 but only 8 in 1,000 are expected to get it of those on the pill.

So far, 200,000 cases of ovarian cancer and 100, 000 deaths from the disease are estimated to have been prevented by taking the pill.

While the pill protects against ovarian cancer, it slightly increases the chances of getting breast and cervical cancer. However, since there is no early test for ovarian cancer, which is often detected late and with a bad prognosis, doctors say that the benefits against ovarian cancer outweigh the small increased risk of getting the other types of cancer.

Dr. Valerie Berel, head of the study, said that oral contraceptives are the first medication that is known to decrease ovarian cancer. Yet, at this point, most doctors do not recommend taking the pill exclusively for its anti-cancer properties, as taking it does come with potential side effects, such as increased risk of blood clots and high blood pressure.

Some experts are calling for better access to oral contraceptives, claiming that they should become available over the counter. As the pill becomes more available worldwide, experts expect the incidence of ovarian cancer to continue to fall.