Last fall, several patients came to me with questions after hearing about the latest report linking the use of birth-control pills with breast cancer, published in Mayo Clinic Proceedings. In what's known as a meta-analysis, scientists reviewed 34 studies, concluding that the use of the pill is associated with an increased risk of premenopausal breast cancer.
This was hardly the first word on the relationship between birth control and breast cancer -- and it won't be the last. But the link isn't entirely surprising. Women's physiology is complex and largely mediated through intricate interfaces of several different hormones. It makes sense, then, that the medical use of hormones could affect many aspects of our health.
But what my patients (and maybe you) tend to wonder about is, what do these and other study results mean for me -- or my daughter, niece, or friends? How should they affect the way we approach birth control? As with most choices concerning women's health, there's no simple, clear-cut answer. Rather, we should look for ways to make conscious, personalized, informed decisions. So let's take a closer look at some of the essential questions about oral contraceptives and cancer.
A. The most common cause of death due to cancer in women age 20 to 59, breast cancer is growing more prevalent, particularly in younger women. For a long time, we've known that a number of factors increase a woman's risk: having family members with breast cancer, starting your period before age 12, going into menopause after age 55, having no children or a first child after age 30, and drinking alcohol daily. So how does the use of birth-control pills weigh in?
Research has yielded mixed results (as is often the case in science). In 1996, scientists analyzing the findings of 54 studies found that current or recent pill users had a small increased risk of developing breast cancer -- especially those who started taking the pill in their teens. But for women who'd discontinued the pill 10 or more years ago, the risk returned to baseline. In 2002, however, another large study found no significant link. In still another report (this one comparing younger and older age groups) the risk of breast cancer appeared highest in those who used birth control in the five years before diagnosis. This was especially true in the younger group.
And then there's the recent Mayo Clinic Proceedings report. As with most studies -- especially meta-analyses, which examine already-completed research -- the science itself has weaknesses. Nevertheless, this analysis again found a relationship between the use of birth-control pills and increased risk of breast cancer -- in this case, premenopausal breast cancer. Compared with women who'd never used oral contraceptives, those who had were shown to have a 19 percent increased risk overall. The increase in risk was significantly higher, 44 percent, for women who used the pill prior to their first full-term pregnancy.
What does this percentage mean? While the rate of premenopausal breast cancer for the general population is about 1 in 50, women who use the pill before having their first child potentially have roughly a 1 in 40 chance of getting the disease.
The fact is, there's no perfect formula to determine your own risk of developing breast cancer. I recommend working with your doctor to discuss all of your risk factors.
A. Using the pill for five or more years also appears to slightly increase the risk of cervical cancer, caused by human papillomavirus (HPV). White Americans who use the pill appear to have an increased risk of liver cancer, although this doesn't hold true for Asian and African-American women.
The contraception-cancer relationship isn't all negative, however. The use of oral contraceptives has been shown to decrease the risk of ovarian and endometrial cancer. This is a big deal, because while ovarian cancer is less prevalent than breast cancer, it's more deadly, and we have no good way to screen for it. For both ovarian and endometrial cancer, studies show that the longer you use the pill, the lower your the risk of the diseases. One year of pill use, for example, lowers your risk of ovarian cancer by 10 to 12 percent; five years lowers it by 50 percent.
Q. Do other forms of hormonal contraceptives, like the patch or the vaginal ring, have the same risk as birth-control pills?
A. The short answer is that we don't know. We don't have enough experience with these newer forms of hormonal contraception to know how their risks might differ from those of the pill. Until we have specific research on these methods, you should presume the risks are the same as with oral contraceptives.
A. This method allows women to take the pill continuously and have a period only every three months or so. (One product in development eliminates periods entirely.) We have no research yet on the health impact of changing your cycle in this way, but to me it intuitively makes sense to think twice about it. By not having one hormone-free week per month, you're increasing your overall hormone exposure, and we know that hormone exposure is tied to breast-cancer risk. But equally important, the continuous-contraception approach doesn't mimic the body's natural rhythms, which I -- and many women -- hold in high regard. The idea of eliminating such a fundamental bodily cycle -- one that women can use to monitor fertility and general health and to stay in touch with their emotional well-being -- gives me pause.
So when my patients ask me about continuous contraception, I advise them to spend some time exploring the reasons they feel drawn to this approach and balancing these reasons with the lack of research.
Q. Where does all this leave me (or my daughter or niece)?
A. We make decisions in the face of uncertainty every day. Most of us feel fairly comfortable with this. When those decisions involve something as serious as our chance of developing cancer, however, the stakes are higher. When it comes to birth-control choices, there's no "right" answer and no "perfect" method. Every form has pros and cons. But by knowing yourself and staying informed about the risks and benefits of the various approaches, you can make a conscious choice.
Once you make a decision, don't forget to revisit it on a regular basis. The research will change, the experience of your body and soul will give you new information, and your life circumstances will continue to evolve. Stay tuned in, and have confidence in knowing that you are making informed choices.
Conscious decisions, as always, start with looking at yourself honestly and nonjudgmentally. Work with a health-care provider you trust, one who's informed both about your health and the latest science on birth control. Keep in mind that you don't have to decide once and for all: I strongly recommend that women -- and couples -- revisit their choice of birth control at least once a year.
1. Consider your priorities.
Think about what's most important to you when it comes to birth control. Never having to think about it? (You may want to consider an IUD.) Effectiveness? (Would getting pregnant right now be a disaster?) Using something more natural? (A barrier method might work well for you.) What about your partner? What factors are important to him?
2. Know (and accept) yourself.
If you're impulsive and know that you'd never use a barrier method reliably, even though you "wish you would," just smile and acknowledge that about yourself. If the pill works great for you, but you feel like you "should" try a more natural method, recognize that birth control is a personal choice; there are no "shoulds." At the same time, examine your fears or preconceptions about different methods. Did the fact that your cousin got pregnant while using a diaphragm lead you to deeply distrust diaphragms? Remember, there is no such thing as perfect birth control.
3. Review your medical history.
Do you have any particular health risks, such as a strong family history of breast cancer or ovarian cancer? If you're not sure, talk to family members. Discuss your health history with your ob-gyn or your primary-care physician. (Keep in mind, too, that the pill has other health risks besides cancer, and potential benefits as well.)
4. Do your homework.
Science changes all the time, and I highly recommend talking to your doctor regularly about the latest findings on birth control. Also be aware of all the alternative methods: how they work, their risks and benefits, and how those may or may not apply to you.
5. Make a decision.
Given all the variables, and knowing who you are, what method do you think will work best for you? Know that you'll revisit this choice later; it's not final unless you or your partner are considering sterilization.
6. Circle back.
A month or two after you have made this decision, revisit it. How do you feel, physically and emotionally, about the choice? At peace, or uneasy? This "re-reflection" allows you to change your decision after you have lived with it for some time, and is something I recommend you do on a regular basis.
Text by Dr. Tracy Gaudet