The effects of anesthetics on chronic pain after breast cancer surgery.

BACKGROUND The incidence and predictive factors for chronic pain after breast cancer surgery have been widely studied. Because it negatively affects patients' daily lives, methods to prevent and reduce chronic pain and its severity should be developed. Our previous study showed that propofol anesthesia has an antihyperalgesic effect under remifentanil-induced hyperalgesia and reduced acute pain compared with sevoflurane anesthesia. In this study, we investigated the hypothesis that propofol would prevent the development and severity of chronic pain after breast cancer surgery, as in acute pain. METHODS A retrospective study was conducted with 175 women (n = 86 in the propofol group and n = 89 in the sevoflurane group) aged 20 to 65 years who underwent breast cancer surgery between March 2007 and December 2008. Patients were followed up by telephone in July 2011. Analysis included incidence, severity, and duration of chronic pain between propofol and sevoflurane groups. Severity was categorized into mild, moderate, and severe pain. Duration of chronic pain was also divided into 3 categories by 1-year time interval. Risk factors associated with the incidence and severity of chronic pain after breast cancer surgery were also identified. RESULTS Chronic pain after breast cancer surgery was more likely to occur in the sevoflurane group compared with the propofol group (95% confidence interval [CI] 1.146-1.809, P = 0.007). Among patients with chronic pain, neither the severity (95% CI 0.516-7.419) nor duration (95% CI 0.106-1.007) differed between patients receiving sevoflurane and propofol. Younger age (95% CI 0.907-0.992, P = 0.021), axillary lymph node dissection (95% CI 1.204-1.898, P = 0.003), 24-hour postoperative morphine consumption (95% CI 1.004-1.116, P = 0.036), and sevoflurane (95% CI 1.146-1.809, P = 0.007) were predictive factors for the development of chronic pain. Higher 24-hour postoperative morphine consumption (95% CI 1.001-1.379, P = 0.049) increased the severity of chronic pain. CONCLUSIONS This study showed that propofol anesthesia was associated with a lower incidence of chronic pain after breast cancer surgery than sevoflurane anesthesia. However, propofol did not have a significant effect on severity and duration of chronic pain. Further prospective studies are needed to confirm the validity of these provocative findings.