Tumour incidence in Swedish women who gave birth following IVF treatment

BACKGROUND: Possible effects on maternal tumour incidence of a full-term pregnancy following IVF treatment with indicated supraphysiologic steroid and peptide hormonal levels in pregnancy remain uncertain. METHODS: National registries were used to compare incidence of non-invasive and invasive tumour disease in Swedish women with live birth following IVF treatment with women with live birth without IVF. RESULTS: The study had a mean follow-up period of 6.2 years in the IVF group and 7.8 years in the non-IVF group, and the mean gestation period (s.d.) for IVF and non-IVF group was 271.0 (21.1) days and 278.5 (14.1) days, respectively. In a multivariate Poisson regression analysis, adjusted rate ratios of 0.70 (0.52-0.92) and 0.93 (0.58-1.43) among IVF women were found for the risk of carcinoma in situ (CIS) of the cervix and breast cancer, respectively. When date of conception plus 1 and 3 years were used as start of follow-up, the rate ratios of CIS of the cervix increased to 0.77 (0.57-1.03) and 0.86 (0.60-1.19), respectively, and the corresponding figures for breast cancer decreased to 0.91 (0.58-1.42) and 0.74 (0.40-1.26). CONCLUSION: Following a relatively short follow-up period, there is little if any increased risk of premenopausal cancer development in women who gave birth after IVF treatment. The women who gave birth after IVF treatment had a decreased incidence of CIS of the cervix and breast cancer, but only the former was statistically significant. However, further studies are necessary to include longer follow-up times.