20 Jul Is There an Increased Risk of Breast Cancer in Women Who Have IVF?
MedicalResearch.com Interview with:
Alexandra W. van den Belt-Dusebout, PhD
Department of Epidemiology
The Netherlands Cancer Institute
MedicalResearch.com: What is the background for this study?
Response: In vitro fertilization (IVF) is commonly used, but because of the relatively recent use of IVF, long-term breast cancer risk is not yet known. Female sex hormones have been shown to affect breast cancer risk. Because sex hormone levels during hormonal stimulation of the ovaries for IVF are up to 10 times higher than in natural cycles, IVF was expected to increase breast cancer risk.
MedicalResearch.com: What are the main findings?
Response: After a median follow-up duration of 21.1 years, breast cancer risk in IVF-treated women was not significantly different from that in the general population and from the risk among women who underwent other fertility treatments. The risk was not increased until more than 20 years after IVF treatment. Moreover, we did not identify possible subgroups at increased risk. The risk did not differ by type of fertility drugs or subfertility diagnosis. Women who had been treated with more than 6 cycles of IVF even had a lower risk of breast cancer than women treated with 1 to 2 cycles. Women who had a low egg yield after hormonal stimulation of the ovaries had a lower risk of breast cancer than women with an average egg yield.
MedicalResearch.com: What should readers take away from your report?
Response: The results of this study are reassuring for women who have had IVF treatments in the past, in the period until 1995 in the Netherlands. In other countries mostly IVF regimens were quite similar in approximately the same period, with first downregulation followed by hormonal stimulation of the ovaries. We believe that the risks of breast cancer will not be increased for women who have received IVF treatments in other countries, more recently or will undergo IVF in the future, because there were no increased risks in our study in subgroups, especially did the risk of breast cancer not differ by type of fertility drugs or subfertility diagnosis, or even after many cycles and long follow-up. However, future research should be done to confirm this.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: Future research should focus on more recently treated women because different stimulation protocols have been used. However, consequently, follow-up for these women is still shorter than for the studied population. Furthermore, it remains important to follow-up the studied population to evaluate risk of postmenopausal breast cancer, because a large proportion of women did not yet reach menopause.
MedicalResearch.com: Is there anything else you would like to add?
Response: This study is unique because it is a nationwide study comprising a large number of women treated with IVF and other fertility treatments, yet, with detailed treatment information and complete information regarding breast cancer incidence and the most important confounding factors parity and age at first birth, and a median follow-up of more than 20 years.
Furthermore, the risk of breast cancer among IVF-treated women has been compared with the risk in the general population and among women having undergone other fertility treatments.
MedicalResearch.com: Thank you for your contribution to the MedicalResearch.com community.
van den Belt-Dusebout AW, Spaan M, Lambalk CB, et al. Ovarian Stimulation for In Vitro Fertilization and Long-term Risk of Breast Cancer. JAMA. 2016;316(3):300-312. doi:10.1001/jama.2016.9389.
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