Oh Hannah, Arem Hannah, Matthews Charles E, Wentzensen Nicolas, Reding Kerryn W, Brinton Louise A, Anderson Garnet L, Coburn Sally B, Cauley Jane A, Chen Chu, Goodman Deborah, Pfeiffer Ruth M, Falk Roni T, Xu Xia, Trabert Britton
Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD, USA.
Cancer Prevention and Control, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ, USA.
Br J Cancer. 2017 Sep 26;117(7):1070-1078. doi: 10.1038/bjc.2017.268. Epub 2017 Aug 17.
Prolonged sitting and lower levels of physical activity have been associated with increased levels of parent oestrogens (oestrone and oestradiol), the key hormones in female cancers, in postmenopausal women. However, it is unknown whether sitting and physical activity are associated with circulating oestrogen metabolite levels.
Among 1804 postmenopausal women enrolled in the Women's Health Initiative Observational Study, 15 serum oestrogens/oestrogen metabolites were quantified using liquid chromatography-tandem mass spectrometry. Physical activity and sitting were self-reported via questionnaire. Using baseline, cross-sectional data, geometric means (GM) of oestrogens/oestrogen metabolites (pmol l) were estimated using inverse probability weighted linear regression, adjusting for potential confounders and stratified on menopausal hormone therapy (MHT) use.
Longer time spent sitting (⩾10 vs ⩽5h per day) was associated with higher levels of unconjugated oestrone, independent of moderate- to vigorous-intensity physical activity and body mass index, among both never/former (GM=70.6 vs 57.7) and current MHT users (GM=242 vs 179) (P-trend ⩽0.03). Among never/former MHT users, sitting (⩾10 vs ⩽5h per day) was positively associated with 2-methoxyestradiol (GM=16.4 vs 14.4) and 4-methoxyestradiol (GM=2.36 vs 1.98) (P-trend ⩽0.04), independent of parent oestrogens. Inverse associations between moderate- to vigorous-intensity physical activity (⩾15 vs 0 metabolic equivalent task-hours per week) and parent oestrogens were found as expected. After adjustment for parent oestrogens, physical activity was not associated with oestrogen metabolites.
Our data suggest that prolonged sitting and lower moderate- to vigorous-intensity physical activity are associated with higher levels of postmenopausal oestrogens/oestrogen metabolites, the oestrogen metabolism patterns that have previously been associated with higher endometrial and breast cancer risk.
绝经后女性长时间坐着以及较低水平的身体活动与母体雌激素（雌酮和雌二醇）水平升高有关，而母体雌激素是女性癌症中的关键激素。然而，尚不清楚久坐和身体活动是否与循环雌激素代谢物水平相关。
在参与女性健康倡议观察性研究的1804名绝经后女性中，使用液相色谱 - 串联质谱法定量15种血清雌激素/雌激素代谢物。通过问卷自我报告身体活动和久坐情况。利用基线横断面数据，采用逆概率加权线性回归估计雌激素/雌激素代谢物（pmol/l）的几何均值（GM），对潜在混杂因素进行调整，并根据绝经激素治疗（MHT）的使用情况进行分层。
在从未使用/曾经使用MHT的女性（GM = 70.6对57.7）和当前使用MHT的女性（GM = 242对179）中，每天久坐时间较长（≥10小时对≤5小时）与未结合雌酮水平较高相关，与中度至剧烈强度的身体活动和体重指数无关（P趋势≤0.03）。在从未使用/曾经使用MHT的女性中，久坐（≥10小时对≤5小时）与2 - 甲氧基雌二醇（GM = 16.4对14.4）和4 - 甲氧基雌二醇（GM = 2.36对1.98）呈正相关（P趋势≤0.04），与母体雌激素无关。正如预期的那样，发现中度至剧烈强度的身体活动（每周≥15代谢当量任务小时对0）与母体雌激素之间存在负相关。在对母体雌激素进行调整后，身体活动与雌激素代谢物无关。
我们的数据表明，长时间坐着和较低的中度至剧烈强度身体活动与绝经后雌激素/雌激素代谢物水平较高有关，而此前已发现这种雌激素代谢模式与子宫内膜癌和乳腺癌风险较高相关。
