Studies have compared the risk of breast cancer in women who use ovarian stimulating medications to induce ovulation or in conjunction with ovarian stimulation regimens for in vitro fertilization (IVF).
The studies included women from the general community or infertile women not taking ovarian stimulation medications as the two control populations because infertility itself is thought to be a risk factor for breast cancer. It concluded that there were no significant dangers after taking into account case-control studies, randomized controlled trials (RCTs), prospective and retrospective cohort studies, and these investigations. (1)
What do studies say about cancer risk in the IVF process?
Women who had ovarian stimulation medication for infertility treatment and had no prior history of breast cancer were included. Women with any form of prior cancer were not eligible.
Any of the following regimens—CC, gonadotropins like follicle-stimulating hormone/human menopausal gonadotropin, and human chorionic gonadotropin—offered singly or in combination were regarded as the exposure.
Women who were not exposed to ovarian stimulation drugs made up the non-exposed control group. These included either infertile women who did not get ovarian stimulation drug treatment for their infertility or age-matched population controls of women without fertility problems.
The incidence of new clinically or histologically confirmed breast cancer diagnoses (exposed) at any point following ovarian stimulation therapy for infertility in comparison to the non-fertility treatment group is the outcome of interest (control). (3)
Do IVF drugs and supplements increase cancer risk?
The increasing usage of ART treatment cycles called for a deeper analysis of the immediate and long-term effects of ovarian stimulation drugs on tissues that are hormonally sensitive. Although the relationship between fertility medications and ovarian and endometrial malignancies has received substantial documentation, the risk of breast cancer remains unclear.
According to the results of the current study, there was no appreciable increase in the risk of breast cancer in women who had been exposed to ovarian stimulation drugs like CC and gonadotropins when compared to the risk in the general population and infertile women who had not been exposed to these drugs.
Another confusion is the lack of differentiation between superovulation and ovulation induction. CC was solely thought to be utilized in the trials for anovulatory purposes, whereas gonadotropin administration was a component of the ovarian stimulation protocols in an IVF cycle. (4)
What is the statistical result of the studies?
337 of the 5857 women who made up the study base had been exposed to COS. The control group, which consisted of 334 women, could be matched using the predetermined criteria. 63 women (18.7%) had COS for fertility preservation at the time of breast cancer diagnosis, and a total of 274 women had done IVF after completing breast cancer treatment.
For those who underwent IVF after breast cancer treatment (n = 274), the median time from the date of the diagnosis to the first COS exposure was 3.38 years, with a range of 3 months to 12 years. Only three patients had more than five cycles, and the average number of cycles per patient ranged from one (30%) to nine. After being diagnosed with breast cancer, stimulation for fertility preservation began in an average of 49 days (with a range of 6-89). (5)
What is the risk of breast cancer in IVF treatment?
Because there was no detectable increase in the probability of breast cancer recurrence in a matched cohort or after adjusting for some stages, IVF treatment in Turkey as a fertility preservation technique appears to be risk-free in women with pre-existing breast cancer. This is reassuring but can be confusing with the selection of a group of women with a better prognosis than those who did not go through IVF. (2)
1,3,4- Beebeejaun, Y., Athithan, A., Copeland, T. P., Kamath, M. S., Sarris, I., & Sunkara, S. K. (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.
2,5- Fredriksson, A., Rosenberg, E., Einbeigi, Z., Bergh, C., & Strandell, A. (2021). Gonadotrophin stimulation and risk of relapse in breast cancer. Human Reproduction Open, 2021(1), hoaa061.