Executive Summary
Taking oral contraceptives (OCs), even for just a few years, offers significant long-term protection against endometrial cancer, confirms a detailed re-analysis of all available evidence by British researchers.
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Data indicate that the longer a woman takes OCs, the greater her reduction in risk for the disease.
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The most common reason women use the pill is to prevent pregnancy; however, 58% of oc users also cite noncontraceptive health benefits as reasons for using the method. Combined ocs protect against ectopic pregnancy; symptomatic pelvic inflammatory disease; and ovarian, endometrial, and rectal cancer. They also might improve bone health in women with low estrogen levels.
Taking oral contraceptives (OCs), even for just a few years, offers significant long-term protection against endometrial cancer, confirms a detailed re-analysis of all available evidence by British researchers.1 Data indicate that the longer a woman takes OCs, the greater her reduction in risk for the disease, the analysis states.1
Researchers affiliated with the Collaborative Group on Epidemiological Studies on Endometrial Cancer estimate that about 400,000 cases of endometrial cancer have been prevented by OC use in high-income countries from 1965-2014, including about 200,000 in the last decade (2005-2014).
“The strong protective effect of oral contraceptives against endometrial cancer, which persists for decades after stopping the Pill, means that women who use it when they are in their 20s or even younger continue to benefit into their 50s and older, when cancer becomes more common,” said Valerie Beral, FRCOG, FMedSci, professor of epidemiology and co-director of the Cancer Epidemiology Unit at the University of Oxford.
Previous research has shown that the Pill also protects against ovarian cancer, stated Beral, lead author of the analysis, in a statement accompanying the publication. “People used to worry that the Pill might cause cancer, but in the long term, the Pill reduces the risk of getting cancer,” said Beral.
Review the results
To perform the analysis, the researchers pooled data on 27,276 women with endometrial cancer in 36 studies from North America, Europe, Asia, Australia, and South Africa, who represent virtually all the epidemiological evidence collected on the effect of OCs.
Their analysis indicates that every five years of oral contraceptive use reduces the risk of endometrial cancer by about 25%. In high-income countries, at least 10 years of oral contraceptive use reduces the risk of developing endometrial cancer before age 75 from 2.3 to 1.3 cases per 100 users, data suggest.1
While the level of estrogen used in combined OCs has decreased over the years, findings indicate the reduction in endometrial cancer risk was at least as great for women who used the pill during the 1980s as for those who used it in earlier decades. These results suggest that the amount of hormones in the lower-dose pills is still sufficient to reduce the incidence of endometrial cancer, the authors state. The proportional risk reduction did not vary substantially by women’s reproductive history, adiposity, alcohol use, tobacco use, or ethnicity.1
Other health benefits
The most common reason women use the pill is to prevent pregnancy; however, 58% of OC users also cite noncontraceptive health benefits as reasons for using the method.2
Combined OCs protect against ectopic pregnancy; symptomatic pelvic inflammatory disease; and ovarian, endometrial, and rectal cancer.3 They also might improve bone health in women with low estrogen levels.3 The pill also reduces dysmenorrhea, menorrhagia, and anemia, and it is effective in treating dysfunctional uterine bleeding.3 Other potential benefits include prevention of menstrual migraines, treatment of acne, and inducing amenorrhea for lifestyle considerations.4
As the number of U.S. women who are obese grows, so does the number of women with endometrial cancer.5 As weight increases, so does the risk for the disease; obese women are two to three times more likely to develop endometrial cancer.6-8 Obese women, particularly those with central obesity, also are less likely to conceive per cycle.9
Anita Nelson, MD, professor in the Obstetrics and Gynecology Department at the David Geffen School of Medicine at the University of California in Los Angeles, says, “In this epidemic of women who are suffering from obesity-related anovulation, the thought the oral contraceptive could help reduce their risks of endometrial cancer is particularly relevant.”
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Jones RK. Collaborative Group on Epidemiological Studies on Endometrial Cancer. Endometrial cancer and oral contraceptives: An individual participant meta-analysis of 27 276 women with endometrial cancer from 36 epidemiological studies. Lancet Oncol 2015; doi.org/10.1016/S1470-2045(15)00212-0.
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Jones RK. Beyond Birth Control: The Overlooked Benefits of Oral Contraceptive Pills. New York: Guttmacher Institute, 2011.
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Trussell J, Guthrie KG. Choosing a contraceptive. In: Hatcher RA, Trussell J, Nelson AL, et al. Contraceptive Technology: 20th revised edition. New York: Ardent Media; 2011.
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ACOG Practice Bulletin No. 110: Noncontraceptive uses of hormonal contraceptives. Obstet Gynecol 2010; 115(1):206-218.
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Polednak AP. Trends in incidence rates for obesity-associated cancers in the US. Cancer Detect Prev 2003; 27:415-421.
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Reeves GK, Pirie K, Beral V, et al. Cancer incidence and mortality in relation to body mass index in the Million Women Study: Cohort study. BMJ 2007; 335:1134.
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Havrilesky LJ, Maxwell GL, Myers ER. Cost-effectiveness analysis of annual screening strategies for endometrial cancer. Am J Obstet Gynecol 2009; 200(6):640.e1-8.
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Kwon JS, Lu KH. Cost-effectiveness analysis of endometrial cancer prevention strategies for obese women. Obstet Gynecol 2008; 112:56-63.
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Brewer CJ, Balen AH. The adverse effects of obesity on conception and implantation. Reproduction 2010; 140(3):347-364.
