Abstract OT2-01-02: Thoracic interfascial nerve blocks versus paravertebral block for improving quality of recovery after breast cancer surgery: A randomized, double-blind, non-inferiority trial
Authors: Abe H , Horiuchi T , Teramoto A , Tanaka Y , Takei Y , Nagahata T 
Published: May 2019

Background: Chronic pain after breast cancer surgeryhas harmful effects on patients' daily life. Paravertebral block (PVB) can prevent not only acute but chronic pain after breast cancer surgery, although the block is not easily put into practice because of technical difficulty or necessity to change patients' position. Thoracic interfascial nerve blocks (TINB) have been reported that it gives similar analgesic efficacy as PVB as with fewer risks, however there are no reports comparing analgesic efficacy of PVB with TINB. Although there are several scales evaluating postoperative pain including visual analog scale (VAS) or numerical rating scale, Quality of Recovery (QoR) have been set up to assess the impact of postoperative morbidity on patients' ability to return to normal function and quality of life. Among those assessment scales, QoR-40 has been mainly applied. It consists of 40 questions including five dimensions: psychologic support, physical comfort, emotional state, physical independence, and pain. There is a report suggesting that PVB improve QoR-40 after ambulatory breast tumor resection.

Methods: This is a single center single arm phase 2 study for early breast cancer patients. Exclusion criteria are pregnant and parturient women, allergy to local anesthetics, significant psychiatric or mental disorders, and patients with chronic pain. All blocks are subjected to ultrasound guidance. Patients were randomized to receive PVB with 40 ml ropivacaine or TINB with 60 ml ropivacaine. TINB consisted of modified PECS II block and transversus thoracic muscle plane block. For assessment of QoR, QoR-40 score which was consisted of 5 elements including postoperative pain was used. The trial was activated in July 2016.

Statistical Method: We conducted a pilot study on 16 patients who received a PVB during breast cancer surgery. Based on the standard deviation (SD) of QoR-40 on postoperative day (POD) 1, the SD was set to 7.2. Since the non-inferiority limit needs to be reduced to about half as much as the effect quantity used in the average value superiority test, it is set to 8, which is half of the effect quantity 16 in the pilot study. When one-sided test with α error = 0.025 and β error = 0.2, about 13 cases in each group are required. Given that dropout rate is about 30-40%, 18 cases in each group were taken as the number of subject cases.

Results: Thirty-six patients were accrual, 18 of PVB group and 18 of TINB group. Two patients declined the trial, 36/38 (95%) acceptors completed the trial. Total of QoR-40 scores on POD 1 was designated as the primary outcome. For secondary outcomes, both QoR-40 score and pain score were assessed on POD 3 and in postoperative month(s) 1, 3, 6, 12. Other secondary outcomes included pain score by POD 1, incidence of rescue analgesia, time to rescue analgesia, incidence of nausea and vomiting. All patients provided written informed consent before undergoing any study-related procedures.

Conclusions: This trial will provide non-inferiority that TINB preserve the effect of QoR as good as PVB after breast cancer surgery.

If interested, please contact T Horiuchi at t_horiuchi@seichokai.or.jp.

Clinical trial information: UMIN000023340

Citation Format: Abe H, Horiuchi T, Teramoto A, Tanaka Y, Takei Y, Nagahata T. Thoracic interfascial nerve blocks versus paravertebral block for improving quality of recovery after breast cancer surgery: A randomized, double-blind, non-inferiority trial [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT2-01-02.