Taxane modulation of anesthetic sensitivity in surgery for nonmetastatic breast cancer.

Study Objective And Design: The mechanism of action of commonly used general anesthetics is largely unknown. One hypothesized mechanism is through modulation of microtubule stability. Taxanes, a subset of chemotherapeutic drugs known to alter microtubule stability and commonly used to treat breast cancer, offer a natural experiment to test our hypothesis that patients exposed to taxanes prior to surgery, as compared to after surgery, would have a partial resistance to general anesthetics.

Setting, Patients, And Measurements: The anesthetic record of adult women with nonmetastatic breast cancer was used to obtain changes in heart rate and blood pressure surrounding incision, and the amount of inhaled anesthetic agent, induction, and rescue drugs administered.

Main Results: Change in blood pressure in response to incision was significantly higher in the neoadjuvant group (P = .03), whereas change in heart rate was not (P = .53). A greater amount of morphine was administered in the neoadjuvant group (26.3 vs 15.5 mg, P = .02), although not a higher concentration of inhaled anesthetics (P = .15).

Conclusion: These results suggest that the alteration of microtubule stability is one of a number of mechanisms of inhaled anesthetics.