By Sandy Hemphill, Contributing Writer, BabyMed
Dense breast tissue is linked to increased risk for breast cancer. In a recent study of tens of thousands of women, it was found that women who reported a history of infertility treatments were more likely to have denser breast tissue than women who reported no infertility issues. This population-based study was limited to association only, not the reason infertile women have denser breast tissue. While the relationship between denser breast tissue and infertility treatments remains undetermined, a second study suggests part of the problem may be variances in the way radiologists assess mammograms.
Fertility Treatments and Breast Tissue Density
Researchers at Sweden’s Karolinska Instituetet recruited 43,313 women (40 to 69 years old) for a breast cancer risk prediction project between 2010 and 2013. In addition to getting mammograms, each woman completed a questionnaire asking about her age, height, and weight as well as her smoking and alcohol consumption status and family history of breast cancer. Each woman was also asked about any history of infertility.
Of the 8,963 women reporting infertility:
- 1,576 had undergone controlled ovarian stimulation (COS) for in vitro fertilization (IVF).
- 1,429 had other forms of hormonal stimulation that did not include COS.
- 5,948 pursued no fertility treatments.
Mammogram assessments found women who reported history of infertility had denser breast tissue in general than women who did not. Additionally, infertile women who had had COS had denser breasts than infertile women who did not experience hormone treatments.
This study did not explore the cause and effect of denser breast tissue and COS; it merely documented an association in a very large study population. Breast tissue may have been denser than normal before COS treatments began. Indeed, it may be that whatever issue caused a form of fertility that benefited from COS also caused denser breast tissue even before infertility was suspected.
The study also did not document the individual causes of infertility in the women reporting it. It is possible the infertile women who had breast tissue of normal density had infertile male partners but were themselves fertile.
Radiological Interpretation
When assessing a mammogram, there are several radiological interpretation methods in common use. A recent study from Australia put 26 highly experienced radiologists to a test for accuracy. These radiologists:
- Had specialized in radiology an average of 17 years.
- Read an average of 2,072 mammograms each year.
For the study, the radiologists were given mammograms taken at two different angles (40 mammograms total) for 20 women. Breast tissue density was measured using the Volpara Density Grade (VDG) and visual assessment scales recommended by the Royal Australian and New Zealand College of Radiologists. Coincidentally, the Swedish study was based on the Volpara assessment method.
The Australian study found that visual assessments were typically lower (less dense tissue) than indicated on the VDG. The researchers conclude this finding indicates the need for more accurate visual assessment tools for more precise interpretations of mammography tests.
Both studies indicate the value of regular mammograms over an extended time, especially for women who undergo fertility treatments that involve COS and other hormone-stimulation methods. Long-term routine mammographic assessment is also recommended for women who have denser than normal breast tissue and for women with a family history of breast cancer.
Sources:
Lundberg, Frida E, et al. "Association of infertility and fertility treatment with mammographic density in a large screening-based cohort of women: a cross-sectional study."Breast Cancer Research / Springer Science+Business Media 18.36 (2016). BioMed Central. Web. 20 Apr. 2016.
Damases, CN, C Mello-Thomas, and MF McEntee. "Inter-observer variability in mammographic density assessment using Royal Australian and New Zealand College of Radiologists (RANZCR) synoptic scales."PubMed. Journal of Medical Imaging and radiation Oncology / John Wiley & Sons, Inc., 5 Apr. 2016. US National Library of Medicine / National Institutes of Health. Web. 20 Apr. 2016.