Department of Community Medicine, Faculty of Health Sciences, UiT The Arctic University of Norway, 9037, Tromsø, Norway.
Cancer Registry of Norway, Oslo, Norway.
Breast Cancer Res. 2023 Oct 28;25(1):130. doi: 10.1186/s13058-023-01729-x.
Body fatness is a dynamic exposure throughout life. To provide more insight into the association between body mass index (BMI) and postmenopausal breast cancer, we aimed to examine the age at onset, duration, intensity, and trajectories of body fatness in adulthood in relation to risk of breast cancer subtypes.
Based on self-reported anthropometry in the prospective Norwegian Women and Cancer Study, we calculated the age at onset, duration, and intensity of overweight and obesity using linear mixed-effects models. BMI trajectories in adulthood were modeled using group-based trajectory modeling. We used Cox proportional hazards models to calculate hazard ratios (HRs) with 95% confidence intervals (CIs) for the associations between BMI exposures and breast cancer subtypes in 148,866 postmenopausal women.
A total of 7223 incident invasive postmenopausal breast cancer cases occurred during follow-up. Increased overweight duration and age at the onset of overweight or obesity were associated with luminal A-like breast cancer. Significant heterogeneity was observed in the association between age at overweight and overweight duration and the intrinsic-like subtypes (p 0.03). Compared with women who remained at normal weight throughout adulthood, women with a descending BMI trajectory had a reduced risk of luminal A-like breast cancer (HR 0.54, 95% CI 0.33-0.90), whereas women with ascending BMI trajectories were at increased risk (HR 1.09; 95% CI 1.01-1.17 for "Normal-overweight"; HR 1.20; 95% CI 1.07-1.33 for "Normal-obesity"). Overweight duration and weighted cumulative years of overweight and obesity were inversely associated with luminal B-like breast cancer.
In this exploratory analysis, decreasing body fatness from obesity in adulthood was inversely associated with overall, hormone receptor-positive and luminal A-like breast cancer in postmenopausal women. This study highlights the potential health benefits of reducing weight in adulthood and the health risks associated with increasing weight throughout adult life. Moreover, our data provide evidence of intrinsic-like tumor heterogeneity with regard to age at onset and duration of overweight.
体脂是一生中动态变化的暴露因素。为了更深入地了解体重指数（BMI）与绝经后乳腺癌之间的关系，我们旨在研究成年期体脂的起始年龄、持续时间、强度和轨迹与乳腺癌亚型风险之间的关系。
基于前瞻性挪威妇女与癌症研究中自我报告的人体测量数据，我们使用线性混合效应模型计算超重和肥胖的起始年龄、持续时间和强度。使用基于群组的轨迹建模来模拟成年期的 BMI 轨迹。我们使用 Cox 比例风险模型计算风险比（HR）及其 95%置信区间（CI），以评估 BMI 暴露与 148866 名绝经后妇女乳腺癌亚型之间的关系。
在随访期间共发生 7223 例侵袭性绝经后乳腺癌病例。超重持续时间的增加和超重或肥胖的起始年龄与管腔 A 样乳腺癌相关。在超重年龄和超重持续时间与内在样亚型之间的相关性方面观察到显著的异质性（p<0.03）。与成年期一直保持正常体重的女性相比，BMI 呈下降趋势的女性患管腔 A 样乳腺癌的风险降低（HR 0.54，95%CI 0.33-0.90），而 BMI 呈上升趋势的女性患病风险增加（HR 1.09；95%CI 1.01-1.17 为“正常-超重”；HR 1.20；95%CI 1.07-1.33 为“正常-肥胖”）。超重持续时间和超重加权累积年数与管腔 B 样乳腺癌呈负相关。
在这项探索性分析中，成年期从肥胖到体重减轻与绝经后妇女的总体、激素受体阳性和管腔 A 样乳腺癌呈负相关。这项研究强调了在成年期减轻体重的潜在健康益处，以及整个成年期体重增加带来的健康风险。此外，我们的数据提供了与超重起始年龄和持续时间有关的内在样肿瘤异质性的证据。
