Secondary Analysis of the CAN-Study, a Randomised Controlled Trial - Local Anaesthesia and Overall Survival.

Abstract

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. 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. 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). 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. 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. EudraCT number: 2013-002380-25; ClinicalTrials.gov Identifier: NCT01975064.