University of Alberta, Edmonton, Alberta, Canada.
J Clin Oncol. 2013 Apr 20;31(12):1539-47. doi: 10.1200/JCO.2012.45.2722. Epub 2013 Mar 25.
Emerging evidence suggests muscle depletion predicts survival of patients with cancer.
At a cancer center in Alberta, Canada, consecutive patients with cancer (lung or GI; N = 1,473) were assessed at presentation for weight loss history, lumbar skeletal muscle index, and mean muscle attenuation (Hounsfield units) by computed tomography (CT). Univariate and multivariate analyses were conducted. Concordance (c) statistics were used to test predictive accuracy of survival models.
Body mass index (BMI) distribution was 17% obese, 35% overweight, 36% normal weight, and 12% underweight. Patients in all BMI categories varied widely in weight loss, muscle index, and muscle attenuation. Thresholds defining associations between these three variables and survival were determined using optimal stratification. High weight loss, low muscle index, and low muscle attenuation were independently prognostic of survival. A survival model containing conventional covariates (cancer diagnosis, stage, age, performance status) gave a c statistic of 0.73 (95% CI, 0.67 to 0.79), whereas a model ignoring conventional variables and including only BMI, weight loss, muscle index, and muscle attenuation gave a c statistic of 0.92 (95% CI, 0.88 to 0.95; P < .001). Patients who possessed all three of these poor prognostic variables survived 8.4 months (95% CI, 6.5 to 10.3), regardless of whether they presented as obese, overweight, normal weight, or underweight, in contrast to patients who had none of these features, who survived 28.4 months (95% CI, 24.2 to 32.6; P < .001).
CT images reveal otherwise occult muscle depletion. Patients with cancer who are cachexic by the conventional criterion (involuntary weight loss) and by two additional criteria (muscle depletion and low muscle attenuation) share a poor prognosis, regardless of overall body weight.
新出现的证据表明肌肉减少预测癌症患者的生存。
在加拿大艾伯塔省的一个癌症中心，连续评估了患有癌症（肺癌或胃肠道癌；N=1473 例）的患者在就诊时的体重减轻史、腰椎骨骼肌指数和 CT 扫描的平均肌肉衰减（亨氏单位）。进行了单变量和多变量分析。一致性（c）统计用于检验生存模型的预测准确性。
BMI 分布为 17%肥胖、35%超重、36%正常体重和 12%体重不足。所有 BMI 类别中的患者在体重减轻、肌肉指数和肌肉衰减方面差异很大。使用最佳分层确定了这三个变量与生存之间关联的阈值。高体重减轻、低肌肉指数和低肌肉衰减与生存独立相关。包含常规协变量（癌症诊断、分期、年龄、体能状态）的生存模型的 c 统计值为 0.73（95%CI，0.67 至 0.79），而忽略常规变量并仅包含 BMI、体重减轻、肌肉指数和肌肉衰减的模型的 c 统计值为 0.92（95%CI，0.88 至 0.95；P<0.001）。无论患者是否表现为肥胖、超重、正常体重或体重不足，如果存在这三个预后不良的变量，其存活时间为 8.4 个月（95%CI，6.5 至 10.3），而没有这些特征的患者存活时间为 28.4 个月（95%CI，24.2 至 32.6；P<0.001）。
CT 图像显示出隐匿性肌肉减少。通过传统标准（非自愿体重减轻）和另外两个标准（肌肉减少和低肌肉衰减）判断为恶病质的癌症患者，无论总体体重如何，预后均较差。
