Mechanism of isoflurane‑mediated breast cancer growth in vivo.

Use of volatile anesthetics is associated with worse outcome following tumor resection surgery compared with the use of intravenous anesthetics. However, the underlying mechanism has not been clearly delineated yet in vivo. The EO771 cell-based congenic breast cancer model was used in the present study. Isoflurane directly binds to and inhibits two adhesion molecules, leukocyte function-associated antigen-1 (LFA-1) and macrophage-1 antigen (Mac-1). Similarly, exposure to sevoflurane, another volatile anesthetic and LFA-1 inhibitor, is associated with an increase in breast cancer size compared with non-exposure. Thus, the present study first examined the role of LFA-1 and Mac-1 in the EO771 breast cancer model. Both LFA-1 deficiency and inhibition enhanced tumor growth, which was supported by cytokine and eicosanoid data profiles. By contrast, Mac-1 deficiency did not affect tumor growth. The exposure to isoflurane and sevoflurane was associated with an increase in breast cancer size compared with non-exposure. These data suggested that isoflurane enhanced tumor growth by interacting with LFA-1. Isoflurane exposure did not affect tumor growth in LFA-1-deficient mice. In summary, the present data showed that LFA-1 deficiency facilitated breast cancer growth, and isoflurane, an LFA-1 inhibitor, also increased breast cancer growth.