Secondary Analysis of the <scp>CAN</scp> ‐Study, a Randomised Controlled Trial – Local Anaesthesia and Overall Survival

ABSTRACT Introduction This study investigates long‐term survival in the Cancer and Anaesthesia (CAN) study, focusing on the potential impact of local anaesthetic infiltration during breast cancer surgery. A positive effect from peritumoral infiltration has recently been suggested. We conducted an exploratory data analysis to examine a possible association between uncontrolled exposure to local anaesthetics during breast cancer surgery and long‐term survival. Methods Breast cancer patients were recruited to compare long‐term survival according to whether anaesthesia was maintained with inhaled sevoflurane or intravenous propofol. Other aspects of anaesthesia, such as the use of local‐ or regional anaesthesia, were carried out pragmatically according to local institutional guidelines. Kaplan–Meier survival curves were constructed to compare survival between those who received local anaesthetics or not. Results Among 1670 analysed patients, 803 (48.1%) received local anaesthetic infiltration, 67 (4.0%) received a paravertebral block, 75 (4.5%) received both, and 725 (43.4%) received neither. Over a median follow‐up of 76.8 months, no significant differences in overall survival were observed – either between the pooled group of patients who received any local or regional anaesthesia ( n = 945) and those who received neither ( n = 725; p = 0.54), or among all four groups ( p = 0.89). Conclusion We found no association with local‐anaesthetic skin infiltration or regional anaesthesia and long‐term survival in this non‐preplanned secondary analysis of a randomised controlled trial. Editorial Comment In this secondary analysis of an observational follow‐up study for anaesthetic exposure and cancer outcomes, regional or localized local anaesthetic treatments were not associated with a survival advantage. How regional anaesthesia or local anaesthetics might interact with clinical cancer natural history in patients is still not clear, though the results here do not support a large effect. Trial Registration : EudraCT number: 2013‐002380‐25; ClinicalTrials.gov Identifier: NCT01975064