(1) Background: Malnutrition frequently affects patients with cancer, and it negatively impacts treatment tolerance, clinical outcomes and survival. Thus, appropriate nutritional screening and early nutrition support are extremely recommended. Currently, a significant number of oral supplements (OS) are commercially available; despite this, there is a lack of evidence for recommending specific OS, including leucine-enriched OS, for nutritional support in patients with cancer. (2) Aim: To compare the clinical evolution of patients with cancer (undergoing systemic treatment) that received standard hypercaloric, whey protein-based hyperproteic oral supplements vs. hypercaloric, hyperproteic leucine-enriched OS using a novel morphofunctional nutritional evaluation. (3) Patients and methods: This paper details an open-label, controlled clinical study in which patients were randomly assigned to receive nutritional treatment with whey protein-based hyperproteic oral supplements (control group) vs. hypercaloric, hyperproteic leucine-enriched OS (intervention group) during a twelve-week period. Forty-six patients were included; epidemiological, clinical, anthropometric, ultrasound (muscle echography of the rectus femoris muscle of the quadriceps and abdominal adipose tissue) and biochemical evaluation were performed. All patients received additional supplementation with vitamin D. (4) Results: Nutritional parameters (including bioimpedance, anthropometric, ultrasound and biochemical variables) of all included patients remained stable after the nutritional intervention. Extracellular mass tended to increase in the patients that received the leucine-enriched formula. Functionality (evaluated through the stand-up test) improved in both groups (p < 0.001). Prealbumin, transferrin levels and superficial adipose tissue increased in the control group (p < 0.05), while self-reported quality of life improved in all the evaluated patients (p < 0.001). (5) Conclusions: Nutritional support with hypercaloric, hyperproteic (with whey protein) OS and vitamin D supplementation were associated with the maintenance of body composition and improvements in functionality and in quality of life in the patients with cancer undergoing systemic treatment. No significant benefits were observed when a leucine-enriched formula was used.

There is increasing evidence about the role of inflammation in sarcopenia and tumor progression; thus, its modulation would represent a valuable strategy for improving clinical outcomes in patients with cancer. Several studies have reported that whey protein has significant anti-inflammatory and antioxidant characteristics in humans. We aimed to evaluate the effects of whey protein-based oral nutritional support on circulating cytokines in patients with solid tumors undergoing systemic treatment. Forty-six patients with solid tumors of different origin and undergoing systemic treatment were evaluated. Nutritional support with two daily whey protein-based oral supplements was administered. Circulating levels of IL-6, IL-8, IL-10, MCP-1 and IP-10 were determined. Nutritional evaluation included anthropometric, instrumental and biochemical parameters. Over 63% of the evaluated patients underwent surgery, 56.5% required chemotherapy and almost 50% received combined treatment. Patients with resected primary tumor presented with lower baseline IL-6 (p < 0.05) and IP-10 (p < 0.001); after three months of nutritional support, they presented with lower IL-8 (p < 0.05) and tended to present lower IL-6 and IP-10 (p = 0.053 and 0.067, respectively). Significant positive correlations between circulating cytokines, C-reactive protein and ferritin were observed; similarly, negative correlations with anthropometric and biochemical nutritional parameters were noticed (p < 0.05). We did not observe significant changes in circulating cytokine levels (IL-6, IL-8, IL-10, MCP-1 and IP-10) in patients with cancer undergoing systemic treatment after three months of nutritional support with whey protein-based oral supplements. According to a univariate analysis in our cohort, circulating IL-8 was associated with mortality in these patients, additionally, MCP-1 and IP-10 tended to correlate; but an age- and sex-adjusted multivariate analysis revealed that only baseline MCP-1 was significantly associated with mortality (OR 1.03 (95% CI: 1.00–1.05)). In conclusion, surgery of the primary solid tumor and combination treatment allow significant reduction in circulating cytokine levels, which remained stable while patients received nutritional support with whey protein-based oral supplements over three months. The role of MCP-1 as an independent factor for mortality in these patients should be further evaluated.