by Rune Petring Hasselager, PhD student, M.D.
Anesthesia and surgery are fundamental in curable cancer treatment. More than 80% of cancer patients are estimated to benefit from surgery. Since the mid-19th century, when general anesthesia was introduced, surgery has evolved from being a last resort to becoming a strategic, minimally invasive procedure. Additionally, criteria for surgical success have changed from immediate postoperative survival to long-term cancer-free survival. Anesthetic focus has mainly been on short-term recovery; however, increasing evidence suggests that anesthetic techniques may be associated with cancer recurrence after oncologic surgery.
Perioperative surgical stress can induce metastasis formation and tumor growth. Surgical manipulation of the tumor releases malignant cells into the blood stream. Furthermore, the surgical stress caused by surgical trauma creates a favorable environment for tumor cells to seed, spread and grow into distant tissue. This may be the reason why up to one third of persons with colorectal cancer, who are primarily cured by surgery, experience relapse.
Accumulating evidence suggests that the type of anesthesia affects the immune response to surgery and thereby promotes or protects against perioperative metastasis formation. Regional anesthesia may protect against future cancer recurrence in addition to providing excellent postoperative analgesia. Likewise, propofol, a commonly used anesthetic, may have a positive effect on the immune system, while inhalational anesthetic agents may have detrimental effects on metastasis formation. The effect of commonly used analgesics such as NSAID’s and opioids and perioperative glucocorticoids have also been suggested to play important roles in perioperative metastasis formation.
Further research within this field is required to fully understand the pathophysiologic mechanisms behind the hypothesis. If further research supports the hypothesis it will be a quantum leap forward for cancer patient management. The role of the anesthesiologist in the perioperative phase will change from providing clinical homeostasis and analgesia to also include securing optimized immune capability to fight residual cancer cells. Even a small improvement in the anesthetic technique could have an immense effect on recurrence rates for the millions of people undergoing cancer surgery every year.
CSS are currently exploring the analgesic and immune effects of regional anesthesia in a randomized controlled trial of the Transmuscular Quadratus Lumborum (a.k.a. TQL or “TeQuiLa”) nerve block for colon resection. In epidemiologic studies we dive into the effects of glucocorticoids, epidural analgesia and inhalational anesthesia on recurrence after colorectal cancer surgery. Finally, we explore the effects of NSAIDs using in vitro assays of colon cancer dissemination. We look forward to sharing our results within this emerging field of research in the near future.