很少有研究探讨过加速度计测量的身体活动与发生乳腺癌（BC）之间的关系。因此，本研究旨在探讨妇女健康加速度计合作组织（WHAC）成员中加速度计测量的矢量麦克风每15秒计数（VM/15s）和轻度身体活动（LPA）、中等至高强度PA（MVPA）和总体PA（TPA）每日平均分钟数与乳腺癌风险的关联。WHAC共有21,089名绝经后妇女（15,375名来自妇女健康研究 [WHS]，5,714名来自妇女健康倡议客观身体活动和心血管健康研究 [OPACH]）。妇女在髋部佩戴ActiGraph GT3X+ ≥4天，随访7.4年，以确定医师裁定的原位（n = 94）或浸润性（n = 546）乳腺癌。多变量分层Cox回归估计了物理活动测量值的三分位数与总体和队列不同的乳腺癌产生关联的风险比 （HR）和95%置信区间（CI）。通过年龄，种族/族裔和体重指数（BMI）检验效果测量调整。在协变量调整模型中，VM/15s、TPA、LPA和MVPA最高（vs. 最低）三分位数与乳腺癌HR分别为0.80（95% CI，0.64-0.99）、0.84（95% CI，0.69-1.02）、0.89（95% CI，0.73-1.08）和0.81（95% CI，0.64-1.01）。BMI或身体功能的进一步调整削弱了这些关联。VM/15s、MVPA和TPA在OPACH妇女中的关联比WHS妇女更显著；MVPA在年轻妇女中比年长妇女更显著；而LPA在BMI≥30而不是<30 kg/m2的女性中更为显著。加速度计评估的PA水平越高，乳腺癌风险越低。这些关联因年龄和肥胖而有所不同，并且与BMI或身体功能不独立。©2023年美国癌症协会。

Few studies have examined accelerometer-measured physical activity and incident breast cancer (BC). Thus, this study examined associations between accelerometer-measured vector magnitude counts per 15 seconds (VM/15s) and average daily minutes of light physical activity (LPA), moderate-to-vigorous PA (MVPA), and total PA (TPA) and BC risk among women in the Women's Health Accelerometry Collaboration (WHAC).The WHAC comprised 21,089 postmenopausal women (15,375 from the Women's Health Study [WHS]; 5714 from the Women's Health Initiative Objective Physical Activity and Cardiovascular Health Study [OPACH]). Women wore an ActiGraph GT3X+ on the hip for ≥4 days and were followed for 7.4 average years to identify physician-adjudicated in situ (n = 94) or invasive (n = 546) BCs. Multivariable stratified Cox regression estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for tertiles of physical activity measures in association with incident BC overall and by cohort. Effect measure modification was examined by age, race/ethnicity, and body mass index (BMI).In covariate-adjusted models, the highest (vs. lowest) tertiles of VM/15s, TPA, LPA, and MVPA were associated with BC HRs of 0.80 (95% CI, 0.64-0.99), 0.84 (95% CI, 0.69-1.02), 0.89 (95% CI, 0.73-1.08), and 0.81 (95% CI, 0.64-1.01), respectively. Further adjustment for BMI or physical function attenuated these associations. Associations were more pronounced among OPACH than WHS women for VM/15s, MVPA, and TPA; younger than older women for MVPA; and women with BMI ≥30 than <30 kg/m2 for LPA.Greater levels of accelerometer-assessed PA were associated with lower BC risk. Associations varied by age and obesity and were not independent of BMI or physical function.© 2023 American Cancer Society.