In the field of oncology, it is well recognized that a decrease in mass, density, strength, or function of skeletal muscle is associated to increased treatment toxicities and postoperative complications, as well as poor progression-free survival and overall survival. The ability of amino acids to stimulate protein synthesis in cancer patients is reduced. Considering nutritional intervention, this anabolic resistance could be in a part counteracted by increasing protein or by giving specific amino acids. In particular, Leucine might counteract this anabolic resistance not only by increasing substrate availability, but also by directly modulating the anabolic signal pathway. Few studies showed the possibility of increasing muscle protein synthesis by specific nutriments and/or by increasing amino acids or protein administration. In addition, whereas many studies provide evidence of a benefit of adapted physical activity in advanced cancer patients, it is difficult to specify the most appropriate type of exercise, and the optimum rhythm and intensity. Moreover, the benefits of physical activities and of protein support seem greater when it is started at the precachexia stage rather than at the cachexia stage, and their benefits are limited or nonexistent at the stage of refractory cachexia. Future approaches should integrate the combination of several complementary treatments in order to prevent (or improve) cachexia and/or sarcopenia in cancer patients.

中文翻译：

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晚期癌症患者的肌肉蛋白合成代谢：对蛋白质和氨基酸支持以及身体活动的反应。

在肿瘤学领域，众所周知，骨骼肌的质量，密度，强度或功能的下降与治疗毒性和术后并发症的增加以及无进展生存期和总生存期差有关。氨基酸刺激癌症患者蛋白质合成的能力降低。考虑到营养干预，这种合成代谢抗性可能在某种程度上通过增加蛋白质或提供特定氨基酸来抵消。特别地，亮氨酸不仅可以通过增加底物利用率，而且可以通过直接调节合成代谢信号途径来抵消这种合成代谢抗性。很少有研究显示通过特定营养和/或增加氨基酸或蛋白质施用量来增加肌肉蛋白质合成的可能性。此外，尽管许多研究提供了在晚期癌症患者中进行适当体育锻炼的益处的证据，但很难指定最合适的运动类型以及最佳的节律和强度。此外，体育活动和蛋白质支持的益处似乎始于恶病质前阶段而不是恶病质阶段，并且在难治性恶病质阶段其益处有限或不存在。未来的方法应整合几种补充疗法的组合，以预防（或改善）癌症患者的恶病质和/或肌肉减少症。当在恶病质前期而不是恶病质期开始时，体育锻炼和蛋白质支持的益处似乎更大，并且在难治性恶病质阶段它们的益处是有限的或不存在的。未来的方法应整合几种补充疗法的组合，以预防（或改善）癌症患者的恶病质和/或肌肉减少症。当在恶病质前期而不是恶病质期开始时，身体活动和蛋白质支持的益处似乎更大，并且在难治性恶病质阶段它们的益处有限或不存在。未来的方法应整合几种补充疗法的组合，以预防（或改善）癌症患者的恶病质和/或肌肉减少症。