Researchers from the Karolinska Institute in Stockholm, Sweden have recently published an article in Breast Cancer Research which investigates whether infertility and hormonal fertility treatment influence mammographic density, a strong hormone-responsive risk factor for breast cancer.
Key outtakes from the study include:
‘Infertility in couples has an estimated prevalence of 12 to 28 %. Hormonal therapies are commonly used for treating a variety of infertility types.’
‘Since all these treatments increase estrogen and progesterone levels, they have been suspected to influence breast cancer risk. So far, most studies and meta-analyses have found no clear association between ovarian stimulation and breast cancer risk. However, many studies suffer from methodological limitations, including limited control for confounding factors, lack of an appropriate reference group, and short follow-up with small numbers of breast cancer cases among women using hormonal fertility treatment [5].’
‘Mammographic density refers to the amount of radiologically dense fibroglandular tissue in the breast and is a major risk factor for breast cancer [9]. Women with extremely dense breasts have a four- to sixfold higher risk of developing breast cancer compared to women having fatty or non-dense breasts.’
‘Few studies have evaluated the effect of hormone stimulation for fertility treatments on mammographic density.’
‘Cross-sectional study including 43,313 women recruited to the Karolinska Mammography Project between 2010 and 2013. Among women who reported having had infertility, 1576 had gone through COS, 1429 had had hormonal stimulation without COS and 5958 had not received any hormonal fertility treatment.’
‘Percent and absolute mammographic densities were obtained using the volumetric method Volpara™.’
‘After multivariable adjustment, women with a history of infertility had 1.53 cm3 higher absolute dense volume compared to non-infertile women (95 % CI: 0.70 to 2.35). Among infertile women, only those who had gone through COS treatment had a higher absolute dense volume than those who had not received any hormone treatment (adjusted MD 3.22, 95 % CI: 1.10 to 5.33).’
‘No clear associations were observed between infertility, fertility treatment and percent volumetric density.’
‘This may indicate a potential adverse effect of COS, but could also be due to the underlying infertility. Whether this difference in density may affect their potential breast cancer risk is unknown. Hence, continued monitoring of women undergoing COS is warranted.’
