Intrauterine exposures, pregnancy estrogens and breast cancer risk: where do we currently stand?
2006 Study Abstracts
Since 1990, when a hypothesis on intrauterine influences on breast cancer risk was published, several studies have provided supportive, indirect evidence by documenting associations of birth weight and other correlates of the prenatal environment with breast cancer risk in offspring. Recent results from a unique cohort of women with documented exposure to diethylstilbestrol in utero have provided direct evidence in support of a potential role of pregnancy oestrogens on breast cancer risk in offspring.
Since 1992, all US cohorts of DES-exposed persons for whom there was an appropriate comparison group of unexposed persons and for whom there was medical record documentation of exposure (or not) to this substance are being followed in a study supported by the US National Cancer Institute. Slightly more than 4800 women exposed in utero to DES and approximately 2070 unexposed women are included in this cohort. Results concerning breast cancer in offspring have been reported in three reports. The risk for developing breast cancer in the earliest report, when women exposed to DES in utero were still very young (38 years on the average), was barely 18% higher in exposed to nonexposed women. However, the increase became progressively greater with longer follow up.
In the most recent report, for breast cancer occurring at age 40 years or older the risk was significantly higher, by 91%, in women exposed to DES in utero than in those who were not exposed. For breast cancer at age 50 years or older the corresponding excess was 200%, which again was significant but with a wide confidence interval. The overall pattern does not come as a surprise because breast cancer among young women is known frequently to have genetic roots, so an excess risk on account of intrauterine exposure to oestrogens is likely to become more evident with advancing age.
- Full paper (free access) : Intrauterine exposures, pregnancy estrogens and breast cancer risk: where do we currently stand?, Breast Cancer Research, NCBI PubMed PMC1797035, 2006.
- Image credit boram kim.