The Breast Cancer and Contraceptive Pill Link: Let’s Have Some Context
New research suggests what at first glance is a startling increase in the chances of developing breast cancer if a woman uses the particularly high-estrogen versions of the contraceptive pill, but it’s important to put these findings in context.
Researchers from the American Association for Cancer Research, publishing in the journal Cancer Research, looked at the health data and contraceptive history of more than 1,000 women sampled from 1990 to 2009 who used birth control pills and had been diagnosed with invasive breast cancer between the ages of 20 and 49. They compared that with the data of 21,952 women who had never had breast cancer.
The media has turned what those researchers found into a scary sounding statistic: that women who used contraceptive pills were, on average, 50 percent more likely to develop (estrogen receptor-positive) breast cancer than those who had never used oral contraceptives or who had ceased using them 10 years ago. The strongest link was found with high dose estrogen formulation pills. These make up less than one percent of prescriptions filled in the study, but could be linked to a high number of cases. On the other hand, low dose estrogen pills appeared to lead to no elevated breast cancer risk.
The researchers are keen to stress that there are a number of qualifiers for this research:
“Given that these results have not yet been confirmed, and the importance of assessing the many established benefits of oral contraceptives as well as the risks, we are not able to give any clinical recommendations based on this study,” study author Elisabeth F. Beaber is quoted as saying. “It’s an intriguing finding, but there really do need be larger studies with larger sample sizes in different populations to really confirm if these results hold up.”
Contraception opponents will likely seize on this research as proof for their claims that women are at a significant risk of cancers as a result of contraceptives. We should point out, though, that this link isn’t a new finding, and even if it were, the numbers we are talking about are relatively low.
A 1996 analysis of 50 studies by the Collaborative Group on Hormonal Factors in Breast Cancer found that women who were current users of contraceptive pills or had used the contraceptives in the past ten years were more likely to develop breast cancer than those who hadn’t, with the highest risk among women who had continued use since their teenage years. Yet, if the women ceased using oral contraceptives and did not develop breast cancer within ten years, they were no more likely to develop cancer than their non-contraceptive using counterparts after that period.
There are other pieces of research that suggest that the so-called “triphasic” contraceptive regimen slightly increases breast cancer risk, but that finding must be confirmed with multiple trials using larger population samples to confirm the link and ascertain just how strong the connection might be.
This supports what the most recent research suggests: that the formulation of the contraceptive may play a part in the increased cancer risk. It’s also important to unpack the rather startling 50 percent statistic and say how that translates to real-world risk. The increase sounds dramatic but if we consider the thousands of women involved in this study, we begin to put the statistic in context.
For instance, an increase of one woman per 100,000 to two women per 100,000 contracting breast cancer would represent a doubling of the risk but would at the same time represent a very small real-world increase. An exact figures for the increase in breast cancer risk isn’t currently known (different studies offer different but always small increases) but this perhaps suggests how that 50 percent figure might be misleading.
There is also the often barely discussed fact that the contraceptive pill has demonstrated a significant link with lowered risks of ovarian cancer, something that is worth mentioning because that effect is actually quite pronounced and long-lasting, with protection extending even a decade after a woman stops using the pill.
In short, this new research is indeed welcome because it helps to confirm what we already knew. However, it shouldn’t deter women from taking the contraceptive pill. Instead, talking through the health options with a doctor who can discuss both the risks and the benefits of using the contraceptive pill is still recommended because, for most women, the pill is still a sound family planning option.
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