Medical decisions driving the clinical management of octogenarians who require either major or urgent surgery still depend on the patient's age rather than individual functions. This report created the privileged opportunity to illustrate the clinical effectiveness of a comprehensive function-based assessment. This was the case of an 83-year-old gentleman presenting with severe malnutrition and debility due to esophageal cancer. Multidimensional assessments were systematically performed to design the best-tailored therapeutic strategy, including prehabilitation, elective esophagectomy, and emergency laparotomy with ileocolic resection for postoperative hemorrhagic shock due to an occult colonic tumor. This clinical case highlights the need for a systematic and comprehensive assessment of fragile octogenarians, allowing accurate patient evaluation, identification of areas of functional optimization, and establishment of the most appropriate therapeutic decisions.