Many risk factors for breast cancer have been identified. One suspected risk factor is in vitro fertilization (IVF) treatment; however, several studies have been inconclusive because of limited follow-up.
To assess the long-term risk of breast cancer after ovarian stimulation for IVF, researchers analyzed a cohort of 19,158 women who started IVF treatment between 1983 and 1995 (IVF group) and 5950 women starting other fertility treatments between 1980 and 1995 (non-IVF group) at 12 IVF clinics in the Netherlands. The median age at the end of the follow-up period was 53.8 years for the IVF group and 55.3 years for the non-IVF group. Incidence of invasive and in situ breast cancers in women who underwent fertility treatments was obtained through linkage with the Netherlands Cancer Registry.
Among the 25,108 women in the study, 839 cases of invasive breast cancer and 109 cases of in situ breast cancer occurred after a median follow-up of 21.1 years. Breast cancer risk in IVF-treated women was not significantly different from that in the general population or the risk in the non-IVF group. The cumulative incidences of breast cancer at age 55 were 3.0% for the IVF group and 2.9% for the non-IVF group.
The researchers concluded that among women undergoing fertility treatment in the Netherlands between 1980 and 1995, IVF treatment compared with non-IVF treatment was not associated with increased risk of breast cancer after long-term follow-up. Breast cancer risk among IVF-treated women also was not significantly different from that in the general population. For more on the study, click here.