GALENOS 2 is a single-arm, single-center, phase II interventional study designed to evaluate the effects of a galenic immunonutrition dietary supplement in patients with head and neck squamous cell carcinoma, locally advanced rectal cancer, or lung cancer undergoing standard antineoplastic treatment. The study aims to assess whether the formula may reduce treatment-related toxicity and improve treatment compliance, using patients from the GALENOS 1 observational study as the control group for comparison