IVF treatment not linked to breast cancer

Abstract

www.thelancet.com/oncology Vol 17 September 2016 e375 The use of in-vitro fertilisation (IVF) does not increase the risk of breast cancer, according to the fi ndings of a long-term cohort study. There is little knowledge about the possible long-term eff ects of ovarian stimulation for IVF on breast cancer risk. Previous studies have been hindered by having short follow-up periods and small numbers of breast cancers. Furthermore, these studies have provided confl icting results. In a historical cohort study, Alexandra W van den Belt-Dusebout and colleagues (Netherlands Cancer Institute, Amsterdam, Netherlands) set out to explore the eff ect of IVF on the long-term risk of breast cancer after a median follow-up of 21 years. A risk-factor questionnaire was sent to 19 158 women who started IVF treatment between 1983 and 1995 and to 5950 women who were starting other fertility treatments between 1980 and 1995. The incidence of invasive and in-situ breast cancers in women who underwent fertility treatments was obtained through linkage with the Netherlands Cancer Registry (1989–2013). Overall, 839 cases of invasive breast cancer and 109 cases of in-situ breast cancer were identifi ed. The breast cancer r isk in women who received IVF was not significantly different from that in the general population (standardised incidence ratio 1·01, 95% CI 0·93–1·09) or from the risk in the non-IVF group (hazard ratio 1·01, 95% CI 0·86–1·19). The cumulative incidence of breast cancer at age 55 years was 3·0% for the IVF group and 2·9% for the non-IVF group (p=0·85). Lead researcher van den Belt-Dusebout said: “The risk did not increase with larger numbers of IVF cycles or with longer follow-up. We did not identify possible subgroups at increased risk. The risk did not differ by type of fertility drugs or subfertility diagnosis. Although the results are based on women treated in the Netherlands starting IVF treatment between 1983 and 1995, we believe the results are also applicable for women in other developed countries because IVF regimens were similar in different countries in similar periods.” Richard Berks (Breast Cancer Now, London, UK) said: “It has long been unclear whether IVF treatment aff ects a woman’s risk of breast cancer, so this new study providing signifi cant evidence that IVF doesn’t increase the risk will be reassuring to women considering IVF.”