Because of the high incidence of breast cancer and the large numbers of women undergoing ovarian stimulation for IVF, even a small risk increase would have important public health implications.
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The incidence of invasive and in situ, or early stage, breast cancers in women who underwent fertility treatments was obtained through the Netherlands Cancer Registry.
IVF is a form of assisted reproductive technology (ART) that refers to the process of fertilization by manually combining an egg and sperm in a laboratory and then transferring the embryo to the uterus.
Women who undergo in vitro fertilization (IVF) to boost their odds of having a baby aren’t at increased risk of breast cancer, according to Dutch researchers.
Among 25,108 women (average age at study entry, 33 years; average number of IVF cycles, 3.6), 839 cases of invasive breast cancer and 109 cases of in situ breast cancer occurred after a median follow-up of 21 years.
More than 19,000 women who initiated IVF treatment between 1983 and 1995 (IVF group) and almost 6000 women who started other fertility treatments between 1980 and 1995 (non-IVF group), were included in the study cohort.
Interestingly, the female participants who underwent seven or more IVF cycles actually were at a significantly reduced risk of developing breast cancer than those who underwent just one or two rounds of the fertility treatment.
It’s been widely thought that IVF might influence a woman’s risk of breast cancer because it’s a hormonal treatment and there is a well known link between breast cancer and hormones oestrogen and progesterone.
Incidences of breast cancer was three per cent for the IVF group and 2.9 per cent for the non-IVF group.
Relevant Reading: Fertility drugs and the risk of breast cancer: a meta-analysis and review.
“This can be explained by the fact that these women, like women who respond poorly to their first ovarian stimulation, more often reach menopause at an early age”, she said.
“There’s always been some questions about the association between hormones in general and breast cancer risk”, said Clarisa Gracia, director, Fertility Preservation and associate professor of Obstetrics and Gynecology at the Hospital of the University of Pennsylvania.
“For now, the information is helpful to women trying to weigh the risks and benefits of IVF”, she added. Parous women (who had previously given birth) were linked with a significant increased risk in breast cancer versus nulliparous women (HR 1.35, 95% CI 1.16-1.73). In addition, age at menopause and menopausal status were unknown for most women, because most women were not postmenopausal at the questionnaire completion and the study was based on IVF treatment protocols used until 1995. For this reason, experts have speculated that IVF could affect women’s risk for breast cancer.
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Van den Belt-Dusebout disclosed no relevant relationships with industry.
