Along with aging population, cancer incidence and mortality are increasing. However, despite advances in oncology and surgery, long-term survival of cancer patients is far from optimal. Dexmedetomidine is a highly selective alpha 2 adrenergic receptor agonist with sedative, analgesic, and anxiolytic effects. Studies showed that perioperative use of dexmedetomidine reduces delirium and some non-delirium complications after surgery. In long-term follow-up studies of older patients who, for other reasons, were randomized to receive either dexmedetomidine or placebo during intra- or postoperative period, dexmedetomidine use was associated with improved long-term survival. This multicenter randomized trial aims to investigate the effect of perioperative dexmedetomidine on long-term outcomes in older patients undergoing cancer surgery.