Many women worry about the risks of cancer related to oral contraceptives. Few women appreciate that oral contraceptives actually decrease the risk of some cancers in women.
A study published last week in the journal, JAMA Oncology, looked at almost 200,00 women ages 50-71. The study compared those who took oral contraceptives during their reproductive years vs. those who had not.
The study demonstrated that women who had used oral contraceptives for more than 10 years had a 34% decrease in their incidence of endometrial cancer. Women who smoked and were obese, whose risk was greatest, saw the most benefit. Oral contraceptive users had a 40% reduced risk of ovarian cancer, with decreased risk in smokers, the obese, and those who rarely exercised (women in a higher risk category). These results are highly significant.
Additional data did not demonstrate an increase in breath cancer in previous users of oral contraceptives. Colorectal cancer risk was also not increased.
The NIH-AARP Diet and Health Study was prospective and began in 1995 and continued to 2011. The study included at least 100,000 previous users of birth control pills. The decrease in ovarian cancer was similar along modifiable lifestyle factors, and the decrease continued with the duration of use. Similarly, the decrease in uterine cancer strengthened with duration of use.
Physicians believe that these benefits are derived from the changes in uterine and ovarian function in oral contraceptive users. Oral contraceptives provide a level of progesterone that decreases proliferation or growth of the endometrial lining, which is why menstrual bleeding is so much less on the pill . Endometrial cancer is caused by increased growth in the lining of the uterus.
Epithelial ovarian cancer develops from the surface of the ovary. The surface is disrupted each month during ovulation. Oral contraceptives inhibit ovulation and therefore a disruption of the epithelial surface of the ovary. Women who have had pregnancies (lack of ovulation for at least 9 months each time) have fewer ovarian cancers than women who have never conceived.
How does this information apply to women in their later reproductive years? Use of oral contraceptives will provide excellent birth control and regulate menstrual cycles which often become irregular and heavier in the peri-menopausal years. Oral contraceptives can regulate hormone levels during the years when there are more swings in levels which can affect mood, headaches, PMS, etc. In most peri-menopausal women, oral contraceptives can be used until the average age of menopause, age 52, if there are no contraindications such as hypertension, blood clots, and heart disease. Your gynecologist can determine if this is a good option for you.
Marilyn C. Jerome, MD
Foxhall OB-Gyn Associates
New York Times. January 19, 2018. Oral Contraceptives Reduce Risk for Ovarian and Endometrial Cancers
JAMA Oncology. Modification of the Association Between Duration of Oral Contraceptive Use and Ovarian, Endometrial, Breast and Colorectal Cancers. January 18, 2018, by Kara Michels, PhD