Pain after breast surgery is usually treated with narcotics; however, these are associated with a high incidence of side effects such as itching, nausea and vomiting, constipation, urinary retention and dizziness. Another modality for pain control is regional anesthesia; thoracic paravertebral blocks \[TPVB\] using local anesthetics are particularly appealing for breast surgery. They provide good pain control, possibly blunting surgical stress response, and decrease the need for anesthetic agent. However, TPVB are not widely used, and the inherent risk associated with their placement, such as pneumothorax, nerve injury, bleeding and infection, makes them less appealing to patients. From a pain management point of view, paravertebral blocks may be the optimal approach for reducing pain and opiate consumption after breast cancer surgery. In addition, retrospective data suggest a reduction in cancer recurrence if this technique is used. Unfortunately, this effective technique is not widely performed because of the risk of pneumothorax and is only used in some centers. Our intent is to study an alternative approach with fewer risks.
In this study, we will test the ability of intravenous lidocaine to provide pain relief after breast surgery. We base our hypothesis on a number of previous trials showing significant benefits of intravenous local anesthetics in the setting of abdominal surgery1-4.
Approximately 30 to 50% of patients will develop chronic pain following mastectomy5,6. It has been suggested that adequately treating pain in the immediate perioperative period will prevent chronic pain. Specifically, application of EMLA (local anesthetic) cream perioperatively during breast surgery has been shown to reduce the incidence of chronic pain development7. Perioperative administration of intravenous lidocaine may offer similar benefits. Therefore, we will study the incidence of chronic pain in our population after 6 months.
Finally, anesthetic choice during primary surgical intervention for cancer may affect recurrence and metastasis. A recent retrospective study suggests a profound reduction in recurrence in breast cancer patients receiving regional + general anesthesia as compared with general alone9. Similar data have been published in abstract form regarding recurrence after prostate surgery10. Also, Christopherson et al studied the long-term survival of 177 patients after resection of colon cancer in a trial of general anesthesia with and without epidural anesthesia and analgesia supplementation for resection of colon cancer. Epidural supplementation was associated with enhanced survival among patients without metastases before 1.46 years8. Although the mechanisms of this beneficial effect are unclear, attenuation of the surgical stress response, modulation of the inflammatory system, and/or decreased requirement for volatile anesthetics and opiates by regional anesthesia are possible mechanisms11. For example, the neural inputs activated during surgical stress may result in activation of promalignant pathways. Morphine has been shown to promote angiogenesis in a model of breast cancer, a key step in tumor development12. In addition, opiates interfere with natural killer cell function13. It is conceivable that the beneficial effect on recurrence might derive from low systemic level of local anesthetics attained during regional anesthesia. A number of studies have demonstrated significant reduction in opiate requirements and a decrease in the magnitude of stress response when local anesthetics are used intravenously1,3,4. If so, systemic administration would be a safer and a simpler way to reach the same goal. We therefore will compare the effect of local anesthetics given intravenously as compared with placebo on cancer recurrence rate.
