Background: The incidence of gastrointestinal cancer increases with age, with approximately 20% of these cases in people over 80 years of age. Due to pre-existing comorbidities, this onco-geriatric population often presents diagnostic and therapeutic challenges. Methods: A systematic review of articles on PubMed was performed to determine the predictive ability of screening tools and their components regarding the occurrence of adverse outcomes in elderly onco-surgical patients with gastrointestinal malignancies. Results: Surgical procedures in this patient cohort, particularly complex resections, may result in increased morbidity and mortality. The decision to treat an elderly patient with curative intent requires sound clinical judgment based on knowledge, consideration of objective parameters, and experience. These patients could potentially be optimized for surgery with the improvement of nutritional and overall performance status as well as with stabilizing comorbidities. Conclusion: Various geriatric assessment and screening tools have been developed to identify risk factors to assist the surgeon and the interdisciplinary team in treatment planning, including the Frailty Assessment Score, Timed Up and Go test, nutritional status, and Activities of Daily Living test. It is important to emphasize that transparent and open communication between the treating surgeon and the patient is crucial in that the patient fully understands the implications of the treatment plan.