恶液质是肿瘤患者最为常见的合并症之一。其中骨骼肌丢失是恶液质的核心表现，特别是肌肉蛋白大量降解导 致骨骼肌萎缩是其重要的病理生理改变。肿瘤状态下，不但其骨骼肌的代谢异于正常代谢，导致能量消耗的增加和无效的 能量利用，导致恶液质发生，而且肌肉微环境的变化与恶液质的发生、发展密切相关，其中由于众多生物因子直接或间接 的作用，均可导致肌肉蛋白分解，骨骼肌萎缩，促使恶液质发生、发展。恶液质是肿瘤患者死亡的主要原因之一，它不仅 出现在近一半的恶性肿瘤患者中，而且还占据了恶性肿瘤患者死亡原因的20%~40%，并随进程发展而加重。由于恶液质状 态下的骨骼肌萎缩与应激、饥饿等情况引起的骨骼肌萎缩机制大相径庭，且后果比较严重，目前干预手段不可逆转其进程， 所以定期精确测量患者人体体成分就显得尤为重要，动态观察骨骼肌变化，尽早发现，及时干预。

Cachexia is one of the most common complications of cancer. The prominent clinical feature of cachexia is muscle wasting. And protein degradation in skeletal muscle is important in the pathophysiology of cachexia. Cachexia can caused by abnormal metabolism of skeletal muscle in cancer patients resulting from increased energy expenditure and invalid energy utilization. Also, the muscle microenvironment is closely associated with the development of cachexia, many biological factors could directly or indirectly lead to proteolysis and skeletal muscle atrophy. It is estimated that cachexia occurs in half of cancer patients, and is responsible for the death of 20%~40% of malignant cancer patients. Cachexia is distinct from starvation, stress-related loss of muscle mass and has severe consequences. Current interventions cannot reverse its process; therefore, it is important to measure body composition, observe the dynamic changes of skeletal muscle and implement nutritional intervention as early as possible.