(October 11, 2018) The BMJ recently published a study from Denmark about the effect that newer birth control pills have on ovarian cancer risk. Researchers focused on two kinds of pills, those which contained both estrogen and progestogen or those which only had progestogen. In this study, rather than having a specific number of people enrolled, they considered all women between the ages of 19 and 49 years of age with certain exceptions such as those who already had cancer or those treated for infertility. Therefore, instead of tracking the risk of ovarian cancer through number of people, they calculated risk with the number of person years.
Within that population, researchers separated women into three groups, those that have never taken birth control pills, those who currently use them, and those who did use them but no longer do. They found that the first group, those who had never taken birth control pills had the highest incidence of ovarian cancer, at 7.5 cases of ovarian cancer for every 100,000 person years. The other two groups, however, had 3.2 cases for every 100,000 person years. This means that the, “…use of hormonal contraception prevented 21 percent of ovarian cancers in the study population,” explained one of the authors, Lisa Iversen, of the Institute of Applied Health Sciences at the University of Aberdeen.
Eighty-six percent of the study population used a pill that was a combination of estrogen and progestogen so researchers did not have enough evidence to associate progestogen-only pills with ovarian cancer risk.