Fertility treatments provide many positive benefits. However, as is the case with so many medical treatments, there are some potential side effects associated with fertility treatments. One potential side effect associated with certain types of fertility treatments is what is known as altered breast density.
Research Study in Sweden
Researchers at the Karolinska Institutet in Sweden conducted a comprehensive study involving more than 43,000 women between the age of 40 and 69 years. From 2010 to 2013 the participants underwent mammograms for breast cancer risk prediction. Additionally, the women received a questionnaire including questions about age, height, weight, smoking status, alcohol consumption, history of infertility and family history of breast cancer. First, the researchers compared mammographic density levels between fertile and infertile women to assess associations between infertility, hormonal fertility treatments and mammographic density. Then they compared infertile women who had never received hormonal fertility treatment to those who had. The net results of the study included data that suggests that women who have undergone controlled ovarian stimulation as a fertility treatment were more likely to have altered density. According to the leader of the study, Dr. Frida Lundberg, the results of the study would indicate that women with controlled ovarian stimulation might have an increased breast cancer risk.
Breast Density and Cancer
Breasts are composed of two primary types of tissue. There is dense, fibroglandular tissue as well as non-dense, fatty tissue. Healthy breasts consist of both types of tissue, without an undue imbalance between them. Mammographic breast density reflects the tissue composition of the breast as seen on a mammogram. High breast density is an increased risk of developing cancer.
Researchers and medical professionals have long understood that a connection exists between denser breast tissue and a higher incidence of cancer. Thus, the fact that certain fertility treatments alters or increases density becomes an issue when it comes to preventing cancer.
Research studies have revealed that women with a higher density have a four to six times higher risk of cancer than women with a lower density. This underscores the importance of monitoring density when taking certain fertility drugs.
Hormone Replacement Therapy
Certain types of hormone replacement therapies are considered the primary culprits when it comes to the potential for increased breast density and an elevated risk of cancer. This includes hormone replacement therapies like COS. These treatments work to increase estrogen and progesterone levels in a woman’s body, which evidently is the reason for increased density in some cases.
This is the first population-based study to investigate the effect of infertility and hormone stimulation on mammographic density which may be a useful marker for the effect of hormonal fertility treatment on breast cancer risk, especially in women below the age at which breast cancer is normally diagnosed (50 years and older).
The results of the aforementioned research are not conclusive. In fact, at this juncture, the connection between the use of certain fertility treatments and increased density are anecdotal. No firm causal connection has been established because of the manner in which the research was undertaken.
The research study really relied upon self reports from women regarding infertility and the use of fertility treatments, coupled with a determination regarding density. More complete studies examining women as they begin the use of fertility treatments, offset by control groups, will be necessary to absolutely confirm these findings. Nonetheless, there is anecdotal evidence suggesting a real connection between fertility treatments and density in some cases. Consequently, monitoring density before, during and after fertility treatments would seem to be an appropriate step to take at this juncture in time.
As an aside, there was also some evidence derived from this study that some infertile women had higher density than fertile ones. There is a possibility that infertility may also contribute to a higher density in some individuals, even in the absence of fertility treatments involving hormone replacement therapy.
If a woman is concerned about density related issues, and an increase in the risk for breast cancer, there are other types of fertility treatments that may be worth exploring. A doctor can examine options with a patient concerned with density issues or who may already have denser breasts at the outset of proposed fertility treatments.