在肿瘤学领域，解决营养不良和消瘦是一个核心挑战。为了限制肌肉质量的损失，专家们鼓励在癌症治疗中使用蛋白质，但由于它们的对抗效应，这仍然存在争议。事实上，高蛋白摄入量可以保护瘦体重，但可能促进肿瘤生长，而低蛋白饮食可能会减小肿瘤大小，但不能解决消瘦问题。因此，我们使用了一个真实的癌症和化疗模型，评估了不同蛋白质摄入量对消瘦、肿瘤对化疗的反应和免疫系统反应的影响。目标是更深入地了解在接受化疗的癌症患者中蛋白质摄入对其效应的影响。 将雌性Fischer 344大鼠分为六组：五组（每组n = 14）带有癌症（Ward结肠瘤）和化疗的大鼠以等热量的饮食摄取，每组分别含8％、12％、16％、24％或32％的热量来自蛋白质，还有一个健康对照组（n = 8），以含16％蛋白质的饮食为标准。化疗包括两个间隔1周的周期，每个周期包括注射CPT-11（50mg/kg），之后在第二天注射5-氟尿嘧啶（50mg/kg）。每日记录食物摄入量、体重和肿瘤大小。于第9天安乐死大鼠并称重器官。确定体成分，并测量肌肉、肝脏、肠道和肿瘤中的蛋白质含量和蛋白质合成（使用SUnSET方法）。使用流式细胞术探索免疫功能。 癌症和化疗导致体重下降，表现为脂肪质量减小（-56 ± 3％，P < 0.05）和无脂肪质量减小（-8 ± 1％，P < 0.05）。令人惊讶的是，蛋白质饮食对体成分、肌肉或肿瘤参数（重量、蛋白质含量或蛋白质合成）没有影响，但高累积蛋白质摄入与相对较高的体重和高无脂肪质量有正相关。免疫系统受到癌症和化疗的影响，但不受蛋白质摄入量的不同影响。 使用一个真实的癌症和化疗模型，我们首次证明蛋白质摄入对肿瘤生长没有正面或负面调节作用。此外，我们的结果表明，在接受化疗的癌症大鼠中，高累积蛋白质摄入能够适度改善营养状况。尽管出于道德原因，这项研究无法在临床上进行评估，但它对于癌症患者的营养管理提供了重要的贡献。 © 2023 The Authors. Journal of Cachexia, Sarcopenia and Muscle由John Wiley＆Sons Ltd代表Society on Sarcopenia, Cachexia and Wasting Disorders出版。

Combating malnutrition and cachexia is a core challenge in oncology. To limit muscle mass loss, the use of proteins in cancer is encouraged by experts in the field, but it is still debated due to their antagonist effects. Indeed, a high protein intake could preserve lean body mass but may promote tumour growth, whereas a low-protein diet could reduce tumour size but without addressing cachexia. Here we used a realistic rodent model of cancer and chemotherapy to evaluate the influence of different protein intakes on cachexia, tumour response to chemotherapy and immune system response. The goal is to gain a closer understanding of the effect of protein intake in cancer patients undergoing chemotherapy.Female Fischer 344 rats were divided into six groups: five groups (n = 14 per group) with cancer (Ward colon tumour) and chemotherapy were fed with isocaloric diets with 8%, 12%, 16%, 24% or 32% of caloric intake from protein and one healthy control group (n = 8) fed a 16% protein diet, considered as a standard diet. Chemotherapy included two cycles, 1 week apart, each consisting of an injection of CPT-11 (50 mg/kg) followed by 5-fluorouracil (50 mg/kg) the day after. Food intake, body weight, and tumour size were measured daily. On day 9, the rats were euthanized and organs were weighed. Body composition was determined and protein content and protein synthesis (SUnSET method) were measured in the muscle, liver, intestine, and tumour. Immune function was explored by flow cytometry.Cancer and chemotherapy led to a decrease in body weight characterized by a decrease of both fat mass (-56 ± 3%, P < 0.05) and fat-free mass (-8 ± 1%, P < 0.05). Surprisingly, there was no effect of protein diet on body composition, muscle or tumour parameters (weight, protein content, or protein synthesis) but a high cumulative protein intake was positively associated with a high relative body weight and high fat-free mass. The immune system was impacted by cancer and chemotherapy but not by the different amount of protein intake.Using a realistic model of cancer and chemotherapy, we demonstrated for the first time that protein intake did not positively or negatively modulate tumour growth. Moreover, our results suggested that a high cumulative protein intake was able to improve moderately nutritional status in chemotherapy treated cancer rodents. Although this work cannot be evaluated clinically for ethical reasons, it nevertheless brings an essential contribution to nutrition management for cancer patients.© 2023 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of Society on Sarcopenia, Cachexia and Wasting Disorders.