Indiana University School of Medicine, Indianapolis, Indiana.
ECOG-ACRIN Biostatistics Center, Providence, Rhode Island.
J Natl Compr Canc Netw. 2023 Sep;21(9):915-923.e1. doi: 10.6004/jnccn.2023.7045.
Observational data investigating the relationship between body habitus and outcomes in breast cancer have been variable and inconsistent, largely centered in the curative setting and focused on weight-based metrics. This study evaluated the impact of muscle measures on outcomes in patients with metastatic breast cancer receiving endocrine-based therapy.
Baseline CT scans were collected from ECOG-ACRIN E2112, a randomized phase III placebo-controlled study of exemestane with or without entinostat. A CT cross-sectional image at the L3 level was extracted to obtain skeletal muscle mass and attenuation. Low muscle mass (LMM) was defined as skeletal muscle index <41 cm2/m2 and low muscle attenuation (LMA) as muscle density <25 HU or <33 HU if overweight/obese by body mass index (BMI). Multivariable Cox proportional hazard models determined the association between LMM or LMA and progression-free survival (PFS) and overall survival (OS). Correlations between LMM, LMA, and patient-reported outcomes were determined using 2-sample t tests.
Analyzable CT scans and follow-up data were available for 540 of 608 patients. LMM was present in 39% (n=212) of patients and LMA in 56% (n=301). Those with LMA were more likely to have obesity and worse performance status. LMM was not associated with survival (PFS hazard ratio [HR]: 1.13, P=.23; OS HR: 1.05, P=.68), nor was LMA (PFS HR: 1.01, P=.93; OS HR: 1.00, P=.99). BMI was not associated with survival. LMA, but not LMM, was associated with increased frequency of patient-reported muscle aches.
Both low muscle mass and density are prevalent in patients with hormone receptor-positive metastatic breast cancer. Muscle measures correlated with obesity and performance status; however, neither muscle mass nor attenuation were associated with prognosis. Further work is needed to refine body composition measurements and select optimal cutoffs with meaningful endpoints in specific breast cancer populations, particularly those living with metastatic disease.
观察性数据研究了乳腺癌患者的身体形态与结局之间的关系，但结果一直存在差异且不一致，这些研究主要集中在治疗环境中，且侧重于基于体重的指标。本研究评估了肌肉指标对接受内分泌治疗的转移性乳腺癌患者结局的影响。
从 ECOG-ACRIN E2112 中收集基线 CT 扫描，这是一项评估依西美坦联合或不联合恩替诺特治疗转移性乳腺癌的随机 III 期安慰剂对照研究。提取 L3 水平的 CT 横截面图像以获取骨骼肌质量和衰减。低肌肉量（LMM）定义为骨骼肌指数<41cm2/m2，超重/肥胖（根据 BMI）时肌肉密度<25HU 或<33HU 定义为低肌肉衰减（LMA）。多变量 Cox 比例风险模型确定 LMM 或 LMA 与无进展生存期（PFS）和总生存期（OS）之间的关联。使用两样本 t 检验确定 LMM、LMA 与患者报告结果之间的相关性。
可分析的 CT 扫描和随访数据可用于 608 例患者中的 540 例。39%（n=212）的患者存在 LMM，56%（n=301）的患者存在 LMA。LMA 患者更有可能患有肥胖症和更差的体能状态。LMM 与生存无关（PFS 风险比[HR]：1.13，P=.23；OS HR：1.05，P=.68），LMA 也无关（PFS HR：1.01，P=.93；OS HR：1.00，P=.99）。BMI 与生存无关。LMA 与患者报告肌肉疼痛的频率增加相关，而不是 LMM。
在激素受体阳性转移性乳腺癌患者中，低肌肉量和低肌肉密度都很常见。肌肉指标与肥胖症和体能状态相关；然而，肌肉量和衰减均与预后无关。需要进一步工作来改进体成分测量，并在特定乳腺癌人群中选择具有有意义终点的最佳截止值，特别是那些患有转移性疾病的人群。
