Scientific Background Anesthesia and surgery are stressful situations which cause neuro-endocrine, metabolic and neurological responses. Cancer surgery may cause a decrease in anti-angiogenic factors, and enable dissemination of tumor cells through manipulation of the tumor and it blood vessels, as well as local and systemic secretion of growth hormones, and immune suppression. The magnitude of the response depends on many factors, including the extent of tissue injury, technique of anesthesia and type of analgesia, transfusions, temperature changes, psychological stress and genetic factors (1-3). The tissue damage starts a cascade of local and systemic processes which include secretion of hormones and cytokines (1).