British researchers said, the longer a woman is on the pill, the less likely she is to develop the disease known as the "silent killer" because symptoms are often diagnose too late, the Lancet Medical Journal reports that the pill halves the risk of ovarian cancer compared with those who have never taken it.
The report also said that benefits of pill overweigh any other slight rise in cancer risk.
The longer a woman stays on the pill, the lower risk she had for having the disease, which is more common in woman after age 50.
More than 200,000 women worldwide have been prevented from developing ovarian cancer said Valerie Beral of the University of Oxford and colleagues wrote in their report.
