According to a Dutch study, women who have a multiple pregnancy after in vitro fertilization have a 44% increased risk of breast cancer compared to mothers of only one child.
What if multiple pregnancy after in vitro fertilization put women at additional risk of breast cancer? This is in any case what seems to demonstrate a Dutch cohort study presented in London this Tuesday at the congress of the society of reproductive medicine and embryology (ESHRE) and reported by the press agency APM.
According to Els Groeneveld of the University of VU Medical Center in Amsterdam who conducted the study, “It is generally accepted that hormones such as estrogen or progesterone during multiple pregnancy stimulate cell proliferation in the breast. , which increases the likelihood of somatic mutations and therefore breast cancer ”.
The medical explanation most often put forward to explain this phenomenon is described by the Dutch scientist in this study, “it is the sharp increase in the blood concentration of vascular endothelial growth factor that could be the cause of increased risk of breast cancer ”. It was on the basis of this premise that the Amsterdam research team decided to study this potential risk.
This is why they conducted their research on a cohort study bringing together women who have undergone IVF, a population in which the number of multiple pregnancies is artificially increased, explains Els Groeneveld. The team of scientists then relied on data from the Omega cohort made up of 12,589 women treated by IVF and followed for a median of 16.7 years. The authors noted that in the end 38.7% of them had not had a child, 47.9% had had a single child and 13.4% had had a multiple pregnancy.
But, where the results are interesting, it is that the cancer rates in these three different groups observed were respectively 2.2%, 2.6% and 3.4%. Conclusion, there was therefore an increased risk of 44% in the group of multiple pregnancies compared to mothers of only one child.
However, the researchers temper their discovery by specifying that the increased risk of breast cancer in women with multiple pregnancies was statistically significant if all embryo implantations were successful (increased risk of + 86%), when it was not. the case of women who had a multiple pregnancy after incomplete implantation, only + 31%. For the scientists, these results “once again support the hypothesis according to which there would be a link between the capacity of women to succeed with their implantation and the risk of breast cancer”.
But the doctors do not want to be alarmist, however, and specify that “these results do not constitute an incentive to screen women with multiple pregnancies after IVF,” said Els Groeneveld. And the researcher reassured women in conclusion of this study, “we need more studies to confirm this link, and the magnitude of the risk remains low”.
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