Examine the association between obesity and clinical outcomes in early breast cancer and assess if patient, tumor, and treatment characteristics modify such associations in Malmö Diet and Cancer Study patients (MDCS). The MDCS enrolled 17,035 Swedish women from 1991 to 1996. At enrollment, participants' body mass index (BMI), waist circumference and body fat percentage measures were collected. We identified all female MDCS participants with invasive breast cancer from 1991 to 2014. Follow-up began at breast cancer diagnosis and ended at breast cancer recurrence (BCR), death, emigration, or June 8, 2020. The World Health Organization guidelines were used to classify BMI, waist circumference, and body fat percentage into three categories of healthy weight, overweight, and obesity. We fit Cox regression models to compute adjusted hazard ratios (HRs) with 95% confidence intervals (CI) of BCR according to body composition. To evaluate effect measure modification, we stratified Cox models by patient, tumor, and treatment characteristics. In total, 263 BCRs were diagnosed over 12,816 person-years among 1099 breast cancer patients with a median follow-up of 11.1 years. Obesity according to BMI (HR = 1.44 [95%CI 1.00–2.07]), waist circumference (HR = 1.31 [95%CI 0.98–1.77]), and body fat percentage (HR = 1.41 [95%CI 1.02–1.98]) was associated with increased risk of BCR compared with healthy weight. Obesity was stronger associated with BCR in patients with low socioeconomic position (HR = 2.55 [95%CI 1.08–6.02]), larger tumors > 20 mm (HR = 2.68 [95%CI 1.42–5.06]), estrogen-receptor-negative breast cancer (HR = 3.13 [95%CI 1.09–8.97]), and with adjuvant chemotherapy treatment (HR = 2.06 [95%CI 1.08–4.31]). Higher pre-diagnostic BMI, waist circumference, and body fat percentage was associated with increased risk of BCR. The association between obesity and BCR appears dependent on patient, tumor, and treatment characteristics.

中文翻译：

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肥胖和乳腺癌预后：与患者、肿瘤和治疗特征相关的诊断前人体测量指标

检查肥胖与早期乳腺癌临床结果之间的关联，并评估患者、肿瘤和治疗特征是否会改变马尔默饮食和癌症研究患者 (MDCS) 中的这种关联。MDCS 从 1991 年到 1996 年招募了 17,035 名瑞典女性。在招募时，收集了参与者的体重指数 (BMI)、腰围和身体脂肪百分比。我们确定了 1991 年至 2014 年间患有浸润性乳腺癌的所有女性 MDCS 参与者。随访从乳腺癌诊断开始，到乳腺癌复发 (BCR)、死亡、移民或 2020 年 6 月 8 日结束。使用了世界卫生组织指南将BMI、腰围、体脂率分为健康体重、超重、肥胖三类。我们拟合 Cox 回归模型，根据身体成分计算 BCR 的调整后风险比 (HR) 和 95% 置信区间 (CI)。为了评估效果测量修改，我们按患者、肿瘤和治疗特征对 Cox 模型进行分层。总共有 1099 名乳腺癌患者在 12,816 人年中诊断出 263 例 BCR，中位随访时间为 11.1 年。根据 BMI (HR = 1.44 [95%CI 1.00–2.07])、腰围 (HR = 1.31 [95%CI 0.98–1.77]) 和体脂百分比 (HR = 1.41 [95%CI 1.02–1.98]) 确定肥胖程度）与健康体重相比，BCR 风险增加相关。在社会经济地位较低 (HR = 2.55 [95%CI 1.08–6.02])、较大肿瘤 > 20 mm (HR = 2.68 [95%CI 1.42–5.06])、雌激素受体阴性的患者中，肥胖与 BCR 的相关性更强乳腺癌（HR = 3.13 [95% CI 1. 09–8.97]），以及辅助化疗（HR = 2.06 [95%CI 1.08–4.31]）。诊断前较高的 BMI、腰围和体脂百分比与 BCR 风险增加相关。肥胖和 BCR 之间的关联似乎取决于患者、肿瘤和治疗特征。