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.

Along with aging population, cancer incidence and mortality are increasing. Surgical resection remains the mainstay treatment for solid organ cancer. However, despite advances in oncology and surgery, long-term survival of cancer patients is far from optimal. For example, the 5-year survival rate of cancer patients is about 36.9% in China, and the survival rate decreases for about 10% each year in older patients after cancer surgery. How to improve long-term survival after cancer surgery remains an urgent problem to be solved.

Cancer death usually occur after cancer recurrence or metastasis. The development of cancer recurrence or metastasise after surgical resection depends on the balance between the anti-cancer defense function of host and the invasiveness of residual cancer cells. Studies showed that surgery, while resecting cancer mass, also releases cancer cells into the circulation. Surgical stress also impairs cell-mediated immunity and promote cancer growth.

Dexmedetomidine is a highly selective alpha 2 adrenergic receptor agonist with sedative, analgesic, and anxiolytic effects. Studies showed that intraoperative use of dexmedetomidine reduces anesthetic and opioid consumption and relieves surgery-related stress response and inflammation. Studies also showed that perioperative use of dexmedetomidine reduces delirium, a commonly occurred complication in older patients, and some non-delirium complications after surgery.

The effect of perioperative dexmedetomidine on long-term outcomes after cancer surgery remains unclear. In a long-term follow-up of older patients who were randomized to receive either low-dose dexmedetomidine or placebo during intensive care unit stay, dexmedetomidine use was associated with improved survival within 2 years. In a recent long-term follow-up of older patients who were randomized to receive either dexmedetomidine or placebo during surgery, dexmedetomidine use was associated with improved recurrence-free survival.

The investigators hypothesize that perioperative use of dexmedetomidine may improve long-term survival after cancer surgery. This multicenter randomized trial aims to investigate the effect of perioperative dexmedetomidine on long-term outcomes in older patients undergoing cancer surgery.

Inclusion criteria:

1. Aged 60 years or older.
2. Scheduled to undergo radical surgery for cancer under general anesthesia, with an expected surgical duration of 2 hours or longer.
3. Required patient-controlled intravenous analgesia after surgery.

Exclusion criteria:

1. Inability to communicate preoperatively due to visual, auditory, verbal. or other reasons.
2. Surgery for breast cancer or intracranial tumor.
3. Preoperative severe sinus bradycardia (<50 beats per minute), sick sinus syndrome，or second-degree or above atrioventricular block without pacemaker.
4. Severe hepatic dysfunction (Child-Pugh class C).
5. Severe renal dysfunction (requirement of renal replacement therapy before surgery).
6. Enrolled in other clinical studies.