Department of Preventive Medicine, University of Southern California Keck School of Medicine, Los Angeles, CA 90089-9175, USA.
Int J Cancer. 2013 Feb 15;132(4):891-6. doi: 10.1002/ijc.27653. Epub 2012 Jun 28.
We previously reported an inverse association between sleep duration and breast cancer risk in the prospective, population-based Singapore Chinese Health Study (SCHS) cohort (Wu et al., Carcinogenesis 2008;29:1244-8). Sleep duration was significantly positively associated with 6-sulfatoxymelatonin (aMT6s) levels determined in a spot urine, but aMT6s levels in breast cancer cases were lacking (Wu et al., Carcinogenesis 2008;29:1244-8). We updated the sleep duration-breast cancer association with 14 years of follow-up of 34,028 women in the SCHS. In a nested case-control study conducted within the SCHS, randomly timed, prediagnostic urinary aMT6s concentrations were compared between 248 incident breast cancer and 743 individually matched cohort controls. Three female controls were individually matched to each case on age at baseline interview (within 3 years), dialect group, menopausal status, date of baseline interview (within 2 years), date of urine sample collection (within 6 months) and timing of urine collection during the day (within 1 hr). Cox proportional hazards and conditional regression models with appropriate adjustment for confounders were used to examine the sleep- and aMT6s-breast cancer relationships. Breast cancer risk was not significantly associated with sleep duration; adjusted odds ratio (OR) for 9+ vs. ≤ 6 hr is 0.89 [95% confidence interval (95% CI) = 0.64-1.22]. Prediagnostic aMT6s levels did not differ between breast cancer cases and matched controls; adjusted OR for highest versus lowest quartiles is 1.00 (95% CI = 0.64-1.54). We conclude that sleep duration is not significantly associated with breast cancer risk reduction. Melatonin levels derived from randomly timed spot urine are unrelated to breast cancer. Randomly timed, spot urine-derived melatonin levels are noninformative as surrogates of nocturnal melatonin production.
我们之前在一项前瞻性、基于人群的新加坡华人健康研究(SCHS)队列研究中报告了睡眠时间与乳腺癌风险之间的反比关系(Wu 等人,致癌作用 2008 年;29:1244-8)。睡眠时间与单次尿液中测定的 6-硫酸褪黑素(aMT6s)水平呈显著正相关,但乳腺癌病例中缺乏 aMT6s 水平(Wu 等人,致癌作用 2008 年;29:1244-8)。我们使用 SCHS 中 34028 名女性 14 年的随访数据更新了睡眠时间与乳腺癌的关联。在 SCHS 中进行的一项嵌套病例对照研究中,比较了 248 例新发乳腺癌病例和 743 例个体匹配队列对照的随机时间点、预诊断尿 aMT6s 浓度。每例病例与 3 名女性对照相匹配,匹配因素包括基线访谈时的年龄(在 3 年内)、方言组、绝经状态、基线访谈日期(在 2 年内)、尿样采集日期(在 6 个月内)和日间采集时间(在 1 小时内)。使用 Cox 比例风险和条件回归模型,对混杂因素进行适当调整,以检验睡眠与 aMT6s-乳腺癌之间的关系。乳腺癌风险与睡眠时间无显著相关性;9+ 小时与≤6 小时的调整比值比(OR)为 0.89[95%置信区间(95%CI)=0.64-1.22]。乳腺癌病例与匹配对照的预诊断 aMT6s 水平无差异;最高与最低四分位数的调整 OR 为 1.00(95%CI=0.64-1.54)。我们的结论是,睡眠时间与乳腺癌风险降低无显著相关性。随机时间点单次尿褪黑素水平与乳腺癌无关。随机时间点、单次尿褪黑素水平作为夜间褪黑素产生的替代物没有信息价值。