Concerns of a link between fertility treatment and the risk for breast cancer cleared
As there have been concerns over the years that fertility treatment could stimulate estrogen-sensitive precursor breast cancer cells, more than 4000 studies of this issue have been conducted since 1990, and results have been conflicting. A recent large meta-analysis, involving 1.8 million women who were followed for an average of 27 years, found that there is no link between fertility treatment and an increase in the risk for breast cancer. The meta-analysis included the strongest studies performed since 1990; nine retrospective studies, five case-control studies, five prospective studies, and one comparative study. The authors compared breast cancer incidence among women who underwent ovarian stimulation with the incidence in both age-matched unexposed women in the general population and unexposed infertile women. No significant increase in the risk for breast cancer among women treated with any ovarian stimulation drug was found. Additionally, there was also no increased risk upon limiting the analysis to the eight studies in which women were treated with both gonadotropins and clomiphene citrate.
Reference: Beebeejaun, Y., Athithan, A., & Copeland, T. (2021). Risk of breast cancer in women treated with ovarian stimulation drugs for infertility: a systematic review and meta-analysis. Fertility And Sterility, 116(1), 198-207. doi: 10.1016/j.fertnstert.2021.01.044