Anesthetic Management: Can We Influence Outcomes for Cancer Patients?

Cancer continues to be a major cause of morbidity and mortality throughout the world.  According to the World Health Organization (WHO), in the year 2012 there were approximately 14 million new cases of cancer with 8.2 million deaths attributed to cancer (WHO, 2015).  This number is expected to increase by almost seventy percent in the next two decades.  It is estimated one in seven deaths are caused by cancer, and in high income countries it is the second leading cause of death, while in low-middle income countries it is the third leading cause of death (American Cancer Society, 2015)  Many cancers could be prevented secondary to quitting smoking, reduction of alcohol consumption, avoiding excessive sun exposure, and controlling infections with better procedures, vaccinations and treatments.  Despite this, millions of patients will still require treatment and many of them will require anesthesia at some point during this treatment.  It is our duty to provide patients with safe anesthetic management and contribute to their long-term outcomes.

The last several years much attention has been given to anesthetic management and its effects on cancer.  We know that surgery itself can modulate the innate immune response and may have negative effects on cancer, specifically cancer recurrence and metastasis.  During surgical manipulation, micrometastasis are released into the circulation and the protective function of the primary tumor is removed. The probability that these micrometastasis grow and develop depends largely on their ability to proliferate, vascularize, and colonize another organ (Snyder & Greenberg, 2010).  Suppression of cell-mediated immunity (CMI) is a known complication from surgery and depends primarily on the amount of tissue damage, anesthetic drugs utilized, blood loss and transfusion, pain, hypothermia, nocioception, and perioperative anxiety and stress (Ben-Eliyahu, 2003 and Snyder & Greenberg, 2010).  Whether or not these effects negate the benefit from surgery is still inconclusive.  Research is continually being conducted considering perioperative factors that may contribute to modulation of immune function, and what health care providers can do to improve patient care.

Several anesthetic drugs have been evaluated to review their potential impact on morbidity and mortality, and cancer recurrence.  It is proposed opioids may contribute to cancer growth directly via promotion of angiogenesis and inhibition of cellular immunity (Byrne, Levins & Buggy, 2015).  Reducing surgical stress response and amount of opioids administered could contribute to preservation of immune function and reduction of cancer recurrence. Use of multi-modal analgesia such as regional anesthesia, non-steroidal anti-inflammatory (NSAID), and acetaminophen may help reduce amount of opioids consumed.  Additionally, there is growing evidence suggesting use of regional analgesia may increase patients’ time to cancer recurrence and reduce rate of metastasis.  While many of these studies are retrospective in nature and conflicting results have been found, the benefit may prove to be specific to cancer type.  Currently there are several randomized controlled trials underway and we anxiously await these results.  As we continue to provide care to the growing number of patients with cancer, it is imperative to individualize anesthesia for each patient based on their co-morbidities and procedure performed, and make adjustments accordingly with strength of evidence in the literature.