Finstad Sissi Espetvedt, Emaus Aina, Potischman Nancy, Barrett Emily, Furberg Anne-Sofie, Ellison Peter T, Jasienska Grazyna, Thune Inger
Department of Oncology, Ullevål University Hospital, 0407, Oslo, Norway.
Cancer Causes Control. 2009 Mar;20(2):233-42. doi: 10.1007/s10552-008-9238-2. Epub 2008 Oct 14.
Estrogens induce cellular proliferation and are associated with an increased risk of breast cancer. Birth weight and adult body weight have independently been associated with both estrogen levels and breast cancer risk. Thus, we hypothesize that low birth weight, in combination with adult overweight, may influence premenopausal 17beta-estradiol over an entire menstrual cycle of possible importance for breast cancer.
Among 204 healthy women, aged 25-35 years, who participated in the Norwegian EBBA-I Study, birth weight and age at menarche were assessed. Levels of 17beta-estradiol were measured in daily saliva samples over one menstrual cycle using radioimmunoassay (RIA). Measurements of body composition; waist circumference (cm), body mass index (BMI, kg/m(2)), and total fat percentage (DEXA, %) were assessed. Fasting blood samples were drawn, and serum concentrations of lipids and hormones were determined.
The participating women had mean birth weight of 3,389 g and age at menarche 13.1 years. Women within the highest tertile of birth weight had the lowest 17beta-estradiol throughout the menstrual cycle (p = 0.03), and they tended to have a later age at menarche (p = 0.06). When we looked into birth weight in combination with adult-attained weight, we found that women with lower birth weights, combined with excess weight during adulthood, had higher levels of free 17beta-estradiol over an entire menstrual cycle compared with women with high birth weights and adult overweight. Women with birth weights <3,530 g, who later developed excess body weight (waist >or= 84 cm), showed 33% higher 17beta-estradiol concentrations over a menstrual cycle compared with women with higher birth weights (>or=3,530 g) and adult excess body weight (p = 0.03). The association was even more pronounced in women with birth weights <3,220 g, early age at menarche (<12 years), and adult overweight.
Our findings support variation of premenopausal levels of 17beta-estradiol in response to birth weight and energy status in adult life, suggesting that women with low birth weight in combination with adult overweight are put at risk for higher estradiol levels throughout menstrual cycles, which is of possible importance for breast cancer risk.
雌激素可诱导细胞增殖，并与乳腺癌风险增加相关。出生体重和成年体重分别与雌激素水平及乳腺癌风险有关。因此，我们推测低出生体重与成年超重相结合，可能会在整个月经周期影响绝经前17β-雌二醇水平，这对乳腺癌可能具有重要意义。
在参与挪威EBBA-I研究的204名25至35岁健康女性中，评估出生体重和初潮年龄。使用放射免疫分析法（RIA）在一个月经周期内每日采集唾液样本，测量17β-雌二醇水平。评估身体成分测量值；腰围（厘米）、体重指数（BMI，千克/平方米）和总脂肪百分比（双能X线吸收法，%）。采集空腹血样，测定血脂和激素的血清浓度。
参与研究的女性平均出生体重为3389克，初潮年龄为13.1岁。出生体重处于最高三分位数的女性在整个月经周期中17β-雌二醇水平最低（p = 0.03），且她们的初潮年龄往往较晚（p = 0.06）。当我们研究出生体重与成年后体重相结合的情况时，发现出生体重较低且成年后超重的女性在整个月经周期中游离17β-雌二醇水平高于出生体重高且成年后超重的女性。出生体重<3530克且后来体重超标（腰围≥84厘米）的女性在一个月经周期内的17β-雌二醇浓度比出生体重较高（≥3530克）且成年后体重超标的女性高33%（p = 0.03）。这种关联在出生体重<3220克、初潮年龄早（<12岁）且成年后超重的女性中更为明显。
我们的研究结果支持绝经前17β-雌二醇水平会因出生体重和成年后的能量状况而有所变化，这表明出生体重低且成年后超重的女性在整个月经周期中雌二醇水平较高，这对乳腺癌风险可能具有重要意义。
