Abstract PR485

Abstract

Background & Objectives: It has been suggested that the use of paravertebral block (PVB) could decrease the rate of breast cancer recurrence after breast cancer surgery (BCS); however recent studies demonstrate the opposite. We tested the hypothesis that the use of PVB in combination with volatile anesthesia (VA) was associated with longer recurrence free-(RFS) and overall survival (OS) after BCS. Materials & Methods: After obtaining IRB approval, we retrospectively collected data from women who had BCS under general VA with and without PVB analgesia. We developed 2 propensity score models (PSM) to create a matched sample of patients based on important clinical covariates. Five-year estimates for OS and RFS were obtained using the Kaplan-Meier method. The log-rank test was used to compare the survival distributions between the different levels of select categorical variables. The Cox proportional hazards model was used to provide hazard ratio estimates and their corresponding 95% confidence intervals (CIs). Statistically significant covariates from the univariable assessment were then included in multivariable analyses. Results: Of the 792 women who had BCS, 198 (25%) had a PVB. Before PSM, patients receiving a PVB had a lower BMI (p=0.028), were given less opioid intraoperatively (p<0.001), and had a shorter anesthesia duration (p<0.001). The PSM model 1 was created to match both study groups based on the age, BMI, anesthesia duration, surgery type, and ER/PR/HER2 status. 382 patients were matched, n=191 in the PVB group and n=191 patients in the non PVB group. Patient who received PVB had significantly lower opioid consumption (p<0.001). PVB showed a no statistically significant increase in the risk of recurrence [HR=1.20; 95%CI (0.64,2.24), p>0.05]. In the OS analysis, PVB showed a reduction in the risk of death [HR=0.83; 95%CI (0.38,1.83)]; however, the finding was not statistically significant (p>0.05). The PSM model 2 included same covariates of model 1 plus opioid consumption. 166 patients were matched, n=83 in the PVB group and n=83 in the non PVB group. RFS analysis, PVB showed a reduction in the risk of recurrence[HR=0.86; 95%CI (0.33,2.23)]; however, the finding was not statistically significant. In the OS analysis, PVB showed a reduction in the risk of death [HR=0.48; 95%CI (0.14,1.68)]; however, it was not statistically significant.Conclusion: In this retrospective study, no significant associations were found between the use of PVB in combination with VA anesthesia and RFS or OS. The use PSM allowed us to balance on observed study characteristics; however, the findings remained inconclusive.