The Impact of Malnutrition Risk and Perioperative Complications in Gastrointestinal Cancer Patients Undergoing Elective Major Surgery: A Prospective Observational Multicenter Study - Duran-Poveda, Manuel; Rodriguez Caravaca, Gil; Suarez-de-la-Rica, Alejandro; Villar, Diego Rodriguez; Pernaute, Andres Sanchez; Cancer Minchot, Emilia; Breton, Julia Ocon; Diaz-Vico, Tamara; Martinez-Amores, Brezo (Nutrients, 2026)