Most birth control pills contain estrogen, which raises the red flag of breast cancer risk. Some studies have shown increased risk in current and former Pill users. Recently, Pill users got good news from Dr. Valerie Beral, chief of cancer epidemiology at Oxford University, who has performed the most comprehensive review ever of the research investigating the link between the Pill and breast cancer: 54 studies in 25 countries involving more than 150,000 women. Beral found that birth control pills raise a woman's breast cancer risk 24 percent while she is taking them. But as soon as she stops, that risk begins to decline. After 10 years post-Pill, a woman will again have only an average breast cancer risk.