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Thursday, March 8, 2018
Hormonal Contraception Proven to Slightly Increase Risk of Breast Cancer - but Do The Risks Outweigh the Benefits?
A few months ago I was lying in bed, soon to drift off to sleep, when I heard a bing on my cell phone - my Mom. In that text was a link to a New York Times article “Birth Control Pills Still Linked to Breast Cancer, Study Finds” followed by “??!!??” My eye roll ensued. A burgeoning Ob-gyn, I was too interested to ignore this, I of course read the article and couldn’t get back to sleep.
You too may have heard of this major study from Denmark, published this year in the NEJM, which is making waves in the women’s health community. This study used a health registry (“Danish Sex hormone registry”) to look at 1.8 million Danish women ages 15-49, over the course of 11 years, and compare rates of breast cancer among those who used hormonal contraception with those who didn’t. They further broke down the groups into specific type of hormonal contraception used (IUDs, various pill formulations, implants) and duration of use (current use, recent use, and previous use). They adjusted their results to control for various factors that may have affected their outcomes, such as age, education, and parity. They controlled for previous VTE, history of breast cancer and IVF treatments, by not including these women in the study.
After analyzing the results, they found a whopping 1 additional case of breast cancer per 7,690 women - in other words, breast cancer risk was 20% higher in current and recent users of hormonal contraception than in those who had never used it. The risk seems to be linked to duration of use. In women who had used hormonal contraception for >= 5 years, the elevated risk of breast cancer seemed to be raised for at least 5 years after discontinuation. Note: the study did not find ANY increased risk in women who had previously used hormonal birth control for < 5 years.
When comparing preparations they found that the various combinations of combined OCPs generally did not vary in their propensity to increase risk of breast cancer. However, levonorgestrel releasing IUDs seemed to raise breast cancer risk the same as the use of oral levonorgestrel products.
These statistically significant outcomes are - at first glance - jaw dropping. We have already established the relationship between estrogens and breast cancer risk; previous case-controlled studies showed us associations between OCPS containing high doses of estrogen (doses higher than the preparations we currently use) and breast cancer. But our understanding of combined OCPs containing less estrogen, and progestin’s individual role in the increased risk of breast cancer, is definitely murkier.
But when we delve a bit deeper into the results of this study, we must ask some questions: First, is this clinically relevant? The study appears to hold a lot of statistical power; it’s a large prospective cohort study, but is it too large? The 1.8 million women in the study are premenopausal, 15-49 years old - a subgroup of women at a very low risk of getting cancer in the first place. As NPR put it “A 20% increase of a very small number is still a very small number.” When we look at studies that are this large, there are bound to be outliers who develop the disease of interest. And if the baseline incidence rate is extremely low, this “increase in incidence” is going to be a big percentage jump.
Second, are the patients studied applicable to our patient population? The patients looked at were Danish citizens, ages 15-79. They did not mention the racial breakdown of these participants, so one can only assume that the study reflected Denmark’s relatively homogenous Scandinavian population. In America - the original melting pot, and a country approximately 57 x larger than Denmark - can we assume that this population’s breast cancer incidence reflects ours? This relates to racial breakdown but to other risk factors as well. While the authors of the study did fully adjust their data for certain factors such as age, education and parity, they were unable to control for other important factors, such as breastfeeding, age at menarche, alcohol consumption and physical activity, all of which we know play a role in breast cancer risk and absolutely will differ between the U.S. and Denmark.
Additionally, the question of risks versus benefits arises. We know that hormonal contraception use decreases the debilitating symptoms of many female illnesses: endometriosis, fibroids, PCOS, and primary hypogonadism to name a few. Alternatively, hormonal contraception has also been proven to decrease the risk of other cancers such as endometrial, ovarian, and colorectal cancer. Most importantly, hormonal contraception is among our most reliable form of pregnancy prevention. The ability to plan pregnancy is a KEY component of female independence, and a fundamental part of gender equality. Moreover, the risks of pregnancy are major. Recent studies examining maternal mortality rate in the United States have shown an increase in recent years, now reaching 24 deaths per 100,000 live births. Does the relatively minor increased risk of breast cancer associated with hormonal contraception use outweigh the potential physical and social burden of unplanned pregnancy, including death?
Lastly, when considering the larger implications of this research in the U.S, we must acknowledge that this is terrible political timing. In a climate where Planned Parenthood’s funding is under threat of extinction, is this information going to be used as another way to implicate contraception as “the problem” instead of a solution?
Still, the fear of breast cancer in relation to hormonal contraception persists. This new information is a piece of a larger puzzle, something that should be considered when counseling patients on contraception. Patients deserve to know that there may be a small increased risk of breast cancer with hormonal contraception, even with progestin releasing IUDs. Perhaps women with family histories of breast cancer will opt for non-hormonal contraception such as the Paragard. On a larger scale, perhaps THIS will be the flame that ignites the fire to start creating safer forms of hormonal contraception for women, or (gasp) even contraception methods for men….Oh wait. That will never happen.
Monday, February 26, 2018
Victoria Martino, MS4, Women’s Health Pathway