Immunomodulatory Effects of Surgery, Pain, and Opioids in Cancer Patients.

Surgery is the mainstay of therapy for canine and human solid cancers. Alarmingly, evidence suggests that the process of surgery may exacerbate metastasis and accelerate the kinetics of cancer progression. Understanding the mechanisms by which cancer progression is accelerated as a result of surgery may provide pharmacologic interventions. This review discusses surgery-induced cancer progression. It focuses on immunomodulatory properties of anesthesia and opioids and evidence that studies evaluating the role of opioids in tumor progression are indicated. It concludes by discussing why companion animals with spontaneously arising cancer are an ideal model for clinical trials to investigate this phenomenon.