Breast cancer recurs in 20% of patients following intended curative resection. In vitro data indicates that amide local anaesthetics, including lidocaine, inhibit cancer cell metastasis by inhibiting the tyrosine kinase enzyme Src. In a murine breast cancer surgery model, systemic lidocaine reduces postoperative pulmonary metastases. We investigated whether the additional administration of bosutinib (a known Src inhibitor) influences lidocaine’s observed beneficial effect in this in vivo model. Female BALB/c mice (n = 95) were inoculated with 25,000 4T1 cells into the mammary fad pad and after 7 days the resulting tumours were excised under sevoflurane anaesthesia. Experimental animals were randomized to one of four treatments administered intravenously prior to excision: lidocaine, bosutinib, both lidocaine and bosutinib in combination, or saline. Animals were euthanized 14 days post-surgery and lung and liver metastatic colonies were evaluated. Post-mortem serum was analysed for MMP-2 and MMP-9, pro-metastatic enzymes whose expression is influenced by the Src pathway. Lidocaine reduced lung, but not liver metastatic colonies versus sevoflurane alone (p = 0.041), but bosutinib alone had no metastasis-inhibiting effect. When combined with lidocaine, bosutinib reversed the anti-metastatic effect observed with lidocaine on sevoflurane anaesthesia. Only lidocaine alone reduced MMP-2 versus sevoflurane (p = 0.044). Both bosutinib (p = 0.001) and bosutinib/lidocaine combined (p = 0.001) reduced MMP-9 versus sevoflurane, whereas lidocaine alone did not. In a murine surgical breast cancer model, the anti-metastatic effects of lidocaine under sevoflurane anaesthesia are abolished by the Src inhibitor bosutinib, and lidocaine reduces serum MMP-2. These results suggest that lidocaine may act, at least partly, via an inhibitory effect on MMP-2 expression to reduce pulmonary metastasis, but whether this is due to an effect on Src or via another pathway remains unclear.

Cancer is a major global health problem and the second leading cause of death worldwide. When detected early, surgery provides a potentially curative intervention for many solid organ tumours. Unfortunately, cancer frequently recurs postoperatively. Evidence from laboratory and retrospective clinical studies suggests that the choice of anaesthetic and analgesic agents used perioperatively may influence the activity of residual cancer cells and thus affect subsequent recurrence risk. The amide local anaesthetic lidocaine has a well-established role in perioperative therapeutics, whether used systemically as an analgesic agent or in the provision of regional anaesthesia. Under laboratory conditions, lidocaine has been shown to inhibit cancer cell behaviour and exerts beneficial effects on components of the inflammatory and immune responses which are known to affect cancer biology. These findings raise the possibility that lidocaine administered perioperatively as a safe and inexpensive intravenous infusion may provide significant benefits in terms of long term cancer outcomes. However, despite the volume of promising laboratory data, robust prospective clinical evidence supporting beneficial anti-cancer effects of perioperative lidocaine treatment is lacking, although trials are planned to address this. This review provides a state of the art summary of the current knowledge base and recent advances regarding perioperative lidocaine therapy, its biological effects and influence on postoperative cancer outcomes.

Background/Aim: Systemic lidocaine has recently emerged as a promising agent possessing numerous potentially anti-neoplastic effects. In vitro studies suggest that lidocaine may prevent metastasis by acting on the tyrosine kinase enzyme Src. Intravenous lidocaine has been reported to reduce pulmonary metastasis in vivo in a murine breast cancer model, however the beneficial effect is abolished by the Src inhibitor bosutinib. In this study we examined whether lidocaine and/or bosutinib affects 4T1 breast cancer cell activity in vitro and whether any drug interactions similar to that seen in murine models occur. Materials and Methods: 4T1 murine breast cancer cells were exposed to lidocaine and/or bosutinib. Cell viability after 1 h of exposure was measured using the 3-(4,5dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell migration after 24 h of exposure was measured using the Oris™ migration assay. Results: Lidocaine and bosutinib alone or combined inhibited 4T1 cell viability and migration, but only at supratherapeutic concentrations. Bosutinib did not modulate lidocaine's effect on viability or migration at any concentration tested. Conclusion: Although lidocaine may inhibit 4T1 metastasis in vivo, a direct effect on 4T1 cells is not detectable in vitro at non-toxic concentrations and unlike murine model testing, no unusual interaction with bosutinib was detected. Lidocaine's anti-metastatic properties are likely to be complex and multifactorial and difficult to replicate outside of a biological host.