Impact of Specific Oligomeric Supplementation in Oncologic Patients Undergoing Radiotherapy With Malnutrition or at Risk.

Inclusion Criteria: * Patients of legal age (≥18 years). * Oncology patients (with head and neck, lung or rectal cancer) undergoing or about to start radiotherapy treatment. Patients with oesophageal cancer will also be included, as long as the patient is not undergoing PEG. * Patients who are malnourished or at risk of malnutrition according to GLIM criteria. * Patients requiring supplementation with an oligomeric formula with 100% hydrolysed serum lactoprotein and high MCT intake due to gastrointestinal disturbances (either maldigestion or maldigestion, malabsorption or dysmotility) intolerance to polymeric formulations or any other reason as considered by the physician. * Patients who, at the discretion of the investigator, have the ability to answer the questionnaires and follow the procedures detailed in the protocol. * Patients who give written informed consent to participate. Exclusion Criteria: * Patients with galactosemia, allergies and/or intolerances to lactose or any of the compounds of the formula. * Patients receiving nutritional support other than that of the study characteristics or who have received it during the last month. It will be accepted in patients who, being on a polymeric SNO, are advised to change to the oligomeric formula under study, due to gastrointestinal alterations, intolerances or any other reason considered by the doctor. * Patients who have undergone surgery in the last three months. * Patients who have received Enteral Nutrition in the…