4. Discussion
Cancer, muscle mass, gastrointestinal symptoms, cancers, skeletal muscle mass, tumor, metabolic dysregulation, cancer, cardiac dysfunction, inflammation, tumors, head–neck cancer, skeletal muscle loss, malnutrition, muscle mass gain, ACS, anorexia,
CANCERS, TUMOR, CANCER, MALNUTRITION, INFLAMMATION, TUMORS, CHRONIC DISEASES, ADVERSE EFFECTS, TUMOR PROGRESSION, INSULIN RESISTANCE, VITAMIN D DEFICIENCY, MALNUTRITION, PRIMARY TUMOR, STAGE II COLON CANCER, CANCER
The nutritional status is severely affected in most patients with cancer; this condition affects the treatment tolerability and overall survival [Malnutrition affects patients of both the male and female sexes and all age groups. In cancer, malnutrition is a result of a combination of anorexia, gastrointestinal symptoms and metabolic dysregulation, including insulin resistance [It is well known that nutritional support plays a fundamental role in the prevention, treatment and prognosis of both acute and chronic diseases, especially in cancer patients [Currently, several specific nutritional formulas are available, and their use in precise clinical scenarios is recommended; for example, the use of immunonutrition as a part of abdominal surgery programs or even after surgery in patients with head–neck cancer is recommended [In patients with cancer, an adequate supply of protein is necessary for the maintenance and gain of muscle. Specifically, positive muscle protein balance is necessary for increasing skeletal muscle mass; additionally, the availability of postprandial circulating amino acids is required for stimulating muscle protein synthesis [According to the American Cancer Society Nutrition and Physical Activity Guidelines for Cancer Survivors (ACS guidelines), a healthy body weight, physical activity and a diet rich in vegetables, fruits and whole grains was associated with a longer survival in stage III colon cancer patients. Additionally, they reported an inverse association between red meat consumption and seven-year mortality among 992 individuals with stage III colon cancer and suggested that a higher protein intake might be beneficial for these patients [In all subjects, muscle protein synthesis and breakdown are simultaneous ongoing processes; thus, a positive balance should be presented in order to gain muscle mass. Several studies were focused on protein quality for muscle mass gain, since protein composition and amino acids can affect protein balance, and even exercise-induced muscle protein anabolism [In this context, BCAAs (leucine, isoleucine and valine) have a critical role in promoting protein synthesis in muscle tissue, and for that reason, they were investigated as a target for nutritional therapy [Vitamin D deficiency is frequent in cancers of different origin; its supplementation is strongly recommended for promoting bone health and reducing potential cancer risks [Regarding this, whey protein is a dairy-driven product that is usually used to help people change their weight and body composition and increase muscle strength. Specifically, whey protein is characterized by a significant content of essential and branched-chain amino acids; in consequence, it is a high-quality source of protein. It additionally has a rapid absorption and a higher muscle protein synthesis compared with other protein sources [In contrast to the referred previous publications, a recent metanalysis demonstrated that leucine-isolated supplementation did not improve muscle mass and strength in elderly subjects. However, its combination with vitamin D exhibited a significant benefit for muscle strength, handgrip strength, gait speed and general performance in older adults [Furthermore, some studies reported that leucine is linked to iron and hemoglobin metabolism [A recent review of pre-clinical studies found positive implications of leucine supplementation for reducing skeletal muscle loss (since leucin preserves protein synthesis and decreases protein degradation), attenuating cardiac dysfunction, improving immune competence, preserving energy production capacity and decreasing inflammation [Previous publications suggested a specific effect of leucine on decreasing inflammation [This study has some limitations, with the first limitation being the number of participants in each group and the heterogeneity of the primary tumor location. This was also a short intervention (12 weeks), and the daily intake of OS (using an adherence scale) was not assessed. Additionally, tumor markers were not included. Several reasons explain this exclusion; first, tumor progression was not the goal of this study, and the primary site and stage at the diagnosis were heterogenous, which would have limited the conclusions. It is important to mention that the treatment tolerance was similar in both groups after the first week and until the twelfth week of treatment, but specific day-per-day adherence was not assessed in this study. The gastrointestinal symptoms are frequent in patients with cancer due to systemic treatment-related adverse effects and the local effects of the tumor [In contrast, this study has several strengths; first of all, it is a real reflection of the clinical practice, in which patients with tumors of different locations and stages undergo different lines of systemic treatment and require an appropriate nutritional evaluation combined with early nutritional support. Additionally, we performed a head-to-head comparison of two different OS in cancer patients undergoing systemic treatment (we did not use the placebo in the control group). Furthermore, a comprehensive nutritional evaluation was performed, including anthropometric, echography, functional and biochemical parameters; finally, vitamin D supplementation was included in order to avoid confounding results.