¿Influye la anestesia en los resultados de la cirugía oncológica?

Abstract

The following quality criteria management is considered in radical surgery for cancer, complete eradication of the tumor with negative surgical margins and without macroscopic residual tumor, adequate removal of lymph nodes and minimal manipulation of the tumor. Despite getting all these objectives, residual non-visible tumor or micrometastasis may persist after tumor resection therefore cancer cells can growth and disseminate depending on the aggressiveness of the tumor and host defenses. Three periopera-tive factors can contribute to cancer advance: a) Surgical manipulation that releases cancer cells to the bloodstream, diminishes cellular immunity, including T helper 1 (TH1) and natural killer (NK) cell activity, decreases anti-angiogenic factors and increases pro-angiogenic factors; b) general anaesthetics, except propofol, diminish cellular immunity; and c) opioids inhibit cellular and hu-moral immunity and promote cancer cell growth. Regional anaesthesia and analgesia block nociceptive affer-ents and decrease or eliminate acute postoperative pain. Combined with general anaesthesia would reduce the consumption of volatile anesthetics, potentially immunosuppressive. These actions preserve immunity due to the decrease of neuroendo-crine and inflammatory response to stress and the consumption of opioids. Experimental studies support this hypothesis. Clinical studies show contradictory results. Since the year 2000, twenty one cancer studies for many types of cancer (breast, prostate, colon and rectum, lung, liver and melanoma) have been published. Sixteen studies are retrospective, 5 studies show positive correlation between epidural analgesia and decrease of cancer recurrence risk. Five studies show partial results and 6 studies did not show any association. Data from 5 prospective studies also show variable results. Differences in clinical studies results may be due to several confounding factors like different histological grading, radio-therapy and chemotherapy used previously, different technical difficulty and radical surgery grade, perioperative anaemia, bled, transfusion or hypothermia. Other causes of conflicting results are related to anaesthetic technique and the use or not of intra-operative epidural analgesia. The administration of drugs with potential immunosuppressive effects like non-steroidal anti-in-flammatory drugs, tramadol, beta blockers and statins can also mask the results. There exist moreover methodological problems like small sample size to get a potential positive effect less than 30 %, patients, surgical procedures and old series heterogeneity and finally difficulty to isolate an effect from the complex and multi-factorial perioperative environment. Many outstanding questions are waiting for prospective trials that end within 3 to 7 years. The new laparoscopic approaches , minimally invasive surgery and neoadjuvancy have radically changed the degree of surgical aggression and probably also the impact of the immunoprotective anesthetic techniques on surgical recurrence. Currently there is no evidence that supports one anesthetic technique over another in cancer survival. Key words: Anaesthesia and cancer recurrence. Anaesthesia and metastasis. Analgesia and cancer recurrence. Regional anaesthesia and cancer. RESUMEN Los criterios de calidad en la cirugía oncológica radical se ba-san en la extirpación completa del tumor, con márgenes libres, sin enfermedad macroscópica residual, en una linfadenectomía adecuada y en la mínima manipulación tumoral posible. A pesar de conseguir estos objetivos, tras la extirpación pue-de quedar enfermedad residual no visible o micrometástasis, Recibido: 20-03-13. Aceptado: 30-06-13.