使用CT成像评定晚期胃肠癌的肌肉减少症发生率及其与SGA的相关性
通常被定义为肌肉质量及功能显著丧失的肌肉减少症，近来已被证明是多种疾病状况（包括癌症）不良结局的预测因素。肌肉减少症是肌肉质量消耗的客观指标，通常使用横断面成像模式确定，例如计算机断层扫描（CT）。主观整体评定（SGA）是一种广泛应用于癌症患者的营养评估工具，用于评估癌症患者的营养状况（其中大部分为肌肉质量），并且通常被认为是床边营养评定的“金标准”。虽然二者都可以用于营养状况评估，但是目前二者的相关性并不清楚。
为此，美国癌症治疗中心开展了一项横断面研究，入组2012年8月～2014年10月入住该中心的胃肠道癌症患者84例。利用CT第三腰椎平面肌肉面积除以身高平方计算得出骨骼肌指数（SMI），其中肌肉减少症定义为SMI≤38.5cm²/m²（女性），SMI≤52.4cm²/m²（男性）。
结果发现，肌肉减少症与SGA无显著相关性（P=0.12）。
因此，单独使用SGA评价胃肠癌患者营养状态，并不能有效评估肌肉丢失。联合SGA评定肌肉减少症可能有助于综合了解胃肠癌患者的综合营养状况，预测临床结局。
JPEN J Parenter Enteral Nutr. 2017;41(2):276.
Prevalence of sarcopenia assessed using CT imaging and its correlation with Subjective Global Assessment in advanced gastrointestinal cancer.
Pankaj Vashi; Trisha DaSilva; Amie Nader; Digant Gupta.
Cancer Treatment Centers of America, Zion, Illinois, USA.
PURPOSE: Sarcopenia, which is broadly defined as significant loss of muscle mass and function, has recently been shown to be a predictor of adverse outcomes in a wide range of disease conditions, including cancer. Sarcopenia is an objective marker of muscle mass depletion that is usually determined using cross-sectional imaging modalities such as computed tomography (CT). Subjective Global Assessment (SGA), on the other hand, is a widely used subjective instrument to assess nutrition status (a large component of which is muscle mass) in cancer and is often considered the "gold standard" for bedside nutrition assessment. However, it is not clear whether patients identified as well nourished by the SGA could in fact be sarcopenic and thus more likely to experience adverse outcomes. We therefore evaluated the prevalence of sarcopenia (an objective measure of muscle mass loss) and its correlation with SGA (a subjective measure of muscle mass loss) in patients with gastrointestinal cancer.
METHODS: This was a cross-sectional study of a consecutive case series of 84 patients with gastrointestinal cancer first seen at our institution between August 2012 and October 2014. Using CT imaging, the cross-sectional area of muscles at the L3 vertebral level was measured and then divided by height squared to calculate the skeletal muscle index (SMI)—a measure of sarcopenia. In accordance with previously published literature, sarcopenia was defined as SMI ≤38.5 cm²/m² for women and ≤52.4 cm²/m² for men. SGA was completed within 2 weeks of sarcopenia assessment and classified patients into well nourished, moderately malnourished, and severely malnourished. The correlation between baseline SMI and SGA was evaluated using cross-tabulation analysis and χ² test.
RESULTS: Mean age at presentation was 53.4 years. Forty-eight (57.1%) patients were males while 36 (42.9%) were females. Most common cancers were colon (52.4%), rectum (21.4%), and stomach (17.9%). The majority of tumors was either stage 3 (26.2%) or stage 4 (53.6%). Using SMI, 37 (44%) patients were sarcopenic while 47 (56%) were nonsarcopenic. Using SGA, 51 (60.7%) patients were well nourished while 33 (39.3%) were malnourished. Cross-tabulation analysis between sarcopenia and SGA showed a poor correlation between the 2 measures (P = .12). Of 51 patients classified as well nourished by SGA, 19 (37.3%) were sarcopenic. Similarly, of 33 patients classified as malnourished by SGA, 15 (45.5%) were nonsarcopenic. Further evaluation of those 19 well-nourished sarcopenic patients revealed that they were primarily males (15/19) within the normal body mass index category (9/19).
CONCLUSIONS: Sarcopenia occurred in ~40% of individuals classified as well nourished by SGA. Using SGA alone to evaluate nutrition status in cancer may fail to identify patients with significant muscle mass loss. Our findings underscore the importance of assessing sarcopenia in conjunction with SGA in patients with advanced gastrointestinal cancer to obtain a comprehensive picture of the underlying malnutrition and muscle mass loss. Future research should focus on evaluating the longitudinal relationship between sarcopenia and SGA as well as investigating whether the coexistence of sarcopenia and malnutrition is associated with worse clinical outcomes compared with just either one of those conditions being present.
DOI: 10.1177/0148607116686023