The study was conducted by Dutch researchers (van den Belt-Dusebout et al. non-IVF, JAMA 2016), who followed up over 25,000 women. 19,158 of these women had IVF treatment between 1983 and 1995. 5950 women had non-IVF fertility treatments such as Insemination between 1980 and 1995. The average age of women at the time of the fertility treatment either IVF or non-IVF was around 32 years. These women were followed up for more than 21 years. The average age at the final follow-up for the assessment of the risk of breast cancer was around 54 years.
On average, these women had more than three cycles of IVF. In these women, the risk of breast cancer who had undergone either IVF as fertility treatment or other non-IVF fertility treatments was similar.
Interestingly, the risk of breast cancer in women who had seven or more IVF cycles was less than that of women undergoing one or two IVF cycles. It was also less than that of women who responded poorly to their fertility treatments. There is no obvious explanation for this finding.
This study compares well with another study published before in 2013. The study looked into 87,000 women and had reported no increase in the risk of breast cancer.
Is there a long-term risk of breast cancer?
With these two studies, I can confidently reassure my patients about their long-term risk of breast cancer. What this study confirms is that even with long-term follow-up, the risk of breast cancer is no higher than those women who have not had any fertility treatment. This also holds true for women who had many cycles of either IVF or non-IVF fertility treatments. The risk includes both the invasive and non-invasive (in situ) cancer.
This study provides assurance, but the majority of breast cancer occurs in women over 50 years of age. It would be good to follow up the same women for another few decades, then review the incidence of breast cancer in women exposed to any fertility treatment could be reviewed.
I await such data with much interest. This will help the fertility specialists, like myself, to empower my patients. I want my patients to be able to make informed decisions, whether it’s about their IVF or non-IVF fertility treatments.