Benefits in radical mastectomy protocol: a randomized trial evaluating the use of regional anesthesia

Surgery is the first-line treatment for early, localized, or operable breast cancer. Regional anesthesia during mastectomy may offer the prevention of postoperative pain. One potential protocol is the combination of serratus anterior plane block (SAM block) with pectoral nerve block I (PECS I), but the results and potential benefits are limited. Our study compared general anesthesia with or without SAM block + PECS I during radical mastectomy with axillary node dissection and breast reconstruction using evaluations of pain, opioid consumption, side effects and serum levels of interleukin (IL)-1beta, IL-6 and IL-10. This is a prospective, randomized controlled trial. Fifty patients were randomized to general anesthesia only or general anesthesia associated with SAM block + PECS I (25 per group). The association of SAM block + PECS I with general anesthesia reduced intraoperative fentanyl consumption, morphine use and visual analog pain scale scores in the post-anesthetic care unit (PACU) and at 24 h after surgery. In addition, the anesthetic protocol decreased side effects and sedation 24 h after surgery compared to patients who underwent general anesthesia only. IL-6 levels increased after the surgery compared to baseline levels in both groups, and no differences in IL-10 and IL-1 beta levels were observed. Our protocol improved the outcomes of mastectomy, which highlight the importance of improving mastectomy protocols and focusing on the benefits of regional anesthesia.

was recently investigated and resulted in improved postoperative pain 19 . However, compared with PECS II, the SAM block is an easier and simpler technique that offers long-lasting regional anesthesia 18 . The combination of SAM block + PECS I may provide greater levels of analgesia for radical mastectomy with axillary lymph node dissection and breast reconstruction because of the pattern of analgesia, as previously suggested 20,21 ; however, the results and potential benefits of SAM block + PECS I are very limited considering that these authors evaluated the effectiveness of this combination in only two patients, emphasizing the importance of further studies to validate this alternative surgical approach.
The evaluation of general anesthesia associated with SAM block + PECS I may provide important insights for an alternative anesthetic protocol for this type of mastectomy, but the results and potential benefits are limited. Thus, the aim of our study was to compare general anesthesia associated with SAM block + PECS I to general anesthesia only during radical mastectomy with axillary node dissection and breast reconstruction. The primary outcome measure was pain intensity measured before surgery, in the post-anesthetic care unit (PACU) and at 24 h after surgery. Additionally, it was evaluated opioid consumption, side effects and serum levels of IL-1beta, IL-6 and IL-10. Our results improved the outcomes of mastectomy, which highlight the benefits of regional anesthesia.

Results
A total of 182 surgeries for breast cancer were performed from December 2015 to April 2016, and 133 cases were excluded because of different types of surgical procedures (i.e., mastectomy only, quadrantectomy and lumpectomy), as shown in the CONSORT flowchart (Fig. 1). One patient was excluded for meeting the exclusion criteria (i.e., the presence of chronic pain). A total of 49 patients were randomized to the study. The patients were allocated to the general anesthesia associated with SAM + PECS I protocol (n = 25) or the general anesthesia protocol (n = 24). All patients received the allocated intervention during the surgery, and the follow-up included evaluations in the PACU and at 24 h after surgery. Data from all patients were included in the analysis.
Baseline characteristics. The randomized groups were compared, and the baseline characteristics of the patients are shown in Table 1. There were no differences between groups in age (U = 269.5, p = 0.54), weight (U = 298.0, p = 0.97) or body mass index -BMI (U = 246.0, p = 0.28). The women in the general anesthesia with the SAM block + PECS I group were statistically shorter than the women in the general anesthesia only group (U = 169.0, p = 0.04). There were no intraoperative or postoperative complications in the analyzed patient groups. The SF-36 eight scaled scores, including physical functioning, bodily pain, physical role functioning, general health perceptions, vitality, emotional role functioning, social role functioning and mental health, were evaluated before surgery. The Mann-Whitney test revealed no differences in scores between groups (U = 276.  Secondary outcome -drug consumption. There was a reduction in the intraoperative fentanyl requirement in patients who received general anesthesia associated with SAM + PECS I (U = 119.5, p = 0.0003) compared to patients who received general anesthesia only (Fig. 3A). The intraoperative requirements of propofol (     Figure S1).

Discussion
To our knowledge, this study is the first prospective, randomized study to report that general anesthesia associated with SAM + PECSI in radical mastectomy with axillary node dissection and breast reconstruction reduced the intraoperative consumption of fentanyl, the delivery of morphine in the PACU and at 24 h after surgery and decreased pain intensity and side effects. The baseline characteristics of patients were not different in age, weight, BMI, or overall health status. However, there was a statistically significant difference in height between the groups. The risk factors for breast cancer include weight and BMI 22,23 . A difference in height is not a parameter that would affect the results of regional anesthesia because the most important aspect for calculating the amount of anesthesia is the weight 24,25 .
No block-related complications occurred during the study. In the literature, the incidence of complications is very low, and ultrasound was reportedly a fundamental tool that provided significant improvements in regional anesthesia in breast surgeries, encouraging its iincorporation into the clinical practice for interfascial chest wall blocks [26][27][28][29] .
The association of SAM + PECS I with general anesthesia reduced morphine consumption in the PACU and at 24 h after the procedure. Previous studies have demonstrated that PECS or SAM block reduced opioid consumption in breast cancer surgery 15,17,30,31 . Intraoperative high doses of opioids are associated with long-term chronic pain after mastectomy 32 .
The literature regarding regional anesthesia reports no differences in propofol, cisatracurium and rocuronium consumption 33-35 , which supports our data. The use of SAM block + PECS I decreased pain scores in the PACU and at 24 h after the procedure. An effective postoperative pain control is an essential component to avoid chronic pain, which exhibits very high rates in breast cancer patients after surgery 3 . The role of regional anesthesia in the management of postoperative pain is well known 36 . Specifically, one case report evaluated PECS block for various types of breast surgeries, and the result revealed an excellent intraoperative and postoperative analgesia 37 . A cadaver study suggested that PECS I block produced greater analgesia of the axillary region compared to PECS II block 38 .
Our data demonstrated that the association SAM + PECS I reduced the occurrence of side effects. Consistent with our data, Bashandy and Abbas reported that the use of PECS in mastectomy decreased nausea, vomiting and sedation compared to the use of general anesthesia 17 . A recent meta-analysis supported that regional anesthesia decreased anesthesia side effects 30 .
Cytokines exert inhibitory or excitatory effects on tumor growth depending on their concentrations in the tumor microenvironment, and systemic levels of these mediators may correlate with the disease stage and progression 39 . Furthermore, patients with breast cancer have impaired immune systems 40 . However, no studies have evaluated inflammatory mediators after the association of SAM block + PECS I during radical mastectomy. Our results revealed higher serum levels of IL-6 24 h after surgery, suggesting that the surgical procedure itself was responsible for the increase. This hypothesis is supported by the fact that the surgical procedure modulates the immune system, especially in patients with malignant diseases 41 . Therefore, mastectomy increases IL-6 in cancer-associated adipocytes 42,43 .
There were no differences between groups (general anesthesia versus general anesthesia associated with SAM + PECS I) in IL-6, IL-10 and IL-1 beta levels. Mettler et al. evaluated blood samples of mastectomy or segmental resection patients and demonstrated no difference in the level of IL-1 beta as a consequence of the surgical procedure 41 . Additionally, data from the literature comparing the effects of general anesthesia and regional spinal/ epidural anesthesia in different types of surgeries revealed no difference in IL-1 beta levels compared to anesthesia or the levels before and after the procedure 44,45 . No difference in the anti-inflammatory IL-10 level was observed between groups or before and after the surgical procedure. Tumor cells secrete IL-10 46 especially in breast cancer 47,48 and in the context of the surgery T lymphocytes are the main source of IL-10 release 49 , which may explain the consistent IL-10 levels in our results. One study using paravertebral regional anesthesia reported decreased in IL-1 beta levels and a modest increase in IL-10 levels (10%) without affecting IL-6 compared to the non-blocking group 5 . One of the main reasons for this discrepancy may be the study design, which compared propofol/paravertebral to sevoflurane/opioid. The type of hypnotic used to maintain anesthesia may also affect the cytokine profile. Specifically, IL-1 beta levels increase when sevoflurane is used compared to propofol 50 . Our study reported that serum cytokines exerted a minor influence on the possible beneficial effect of the regional anesthesia on clinical outcomes, as previously suggested 44 .
Surgery is the first choice of treatment, and one of the goals of performing regional anesthesia may be the reduction of post-mastectomy pain syndrome 51 . Regional anesthesia may be an important tool in the reduction of tumor growth and metastasis recurrence 52 . It has been implicated that damage to intercostobrachial nerve could be responsible for persistant pain after breast cancer surgery and the local anesthetic block of this region could be an alternative to prevent this type of pain 53 . Supporting this view, Takimoto demonstrated that SAM block was a treatment modality for chronic neuropathic pain after partial mastectomy 54 .
One limitation of our trial includes the impossibility of measuring the hospital length of stay after surgery. Since no complications were noted, all mastectomy patients were discharged from the hospital three days after the procedure as part of the standardized protocol of the hospital. In addition, serum levels of ropivacaine were not evaluated, which may represent a bias because there are no studies indicating a possible anti-inflammatory effect of ropivacaine.
In conclusion, our results suggest that SAM + PECS I block in association with general anesthetic provides the most effective analgesia for radical mastectomy, but further studies are required.
Implications. This report is the first prospective, randomized, controlled study to report the benefits of general anesthesia associated with SAM block + PECS I in radical mastectomy with breast reconstruction. Our results highlight the importance of improving anesthetic protocols for radical mastectomy and further examining of the benefits of regional anesthesia and pain reduction on the chronification process.

Methods
Patients. The study was a single-center, prospective, randomized controlled clinical trial. The patients participating in the trial were randomly assigned to the group receiving general anesthesia only (standard treatment) or the group general anesthesia associated with SAM block + PECS I. The block randomization method was designed to randomize subjects into groups. It was generated by the corresponding author and included sealed envelopes, and the patients were blinded to this process. An anesthesiologist recruited participants from our ambulatory care unit. The informed consent was provided to all prospective study subjects. The Ethics in Research Committee of the Hospital Sirio Libanes/Brazil Platform approved the project (CAAE 48721715.0.0000.5461), it is registered at Registro Brasileiro de Ensaios Clinicos (ReBEC), ClinicalTrials.gov, Identifier: NCT02647385, and the trial is registered under the name: 'Pain Control in Breast Surgery: Analgesia, Opioid Consumption and Inflammatory Response Evaluation' . The principal investigator's name is Raquel Chacon Ruiz Martinez and the date of registration is 12/28/2015. All methods were performed in accordance with the relevant guidelines and regulations.
The inclusion criteria were female patients aged 18-75 years old who provided written consent, with American Society of Anesthesiology (ASA) physical status I or II, and who were suitable for elective radical mastectomy with axillary node dissection and breast reconstruction. Exclusion criteria were previous allergy to medications used in the study, history of mental disorders and chronic pain. Chronic pain was diagnosed using the Douleur Neuropathique 4 (DN4) questionnaire 55  Primary outcome. The primary outcome measure was pain intensity, which was assessed using visual analog pain scale (VAS) scores before surgery, in the post-anesthetic care unit (PACU) and at 24 h after surgery. The VAS scores range from 0-10, and a blinded experimenter evaluated the VAS scores. Secondary outcomes. Blinded observers evaluated secondary outcomes, which included the consumption of fentanyl and propofol in the intraoperative room, the consumption of PCA-morphine in the PACU and at 24 h after the surgery, the time spent in the PACU, the side effects exhibited in the PACU and at 24 h after the surgery, and serum cytokines IL-1 beta, IL-6 and IL-10 levels before and 24 h after surgery. Any complications were recorded.
SAM Block + PECS I. Three anesthetists who were experienced in performing SAM and PECS I performed these blocks. Prior to the procedure, 2% chlorhexidine solution with 70% isopropyl alcohol and sterile ultrasound conducting gel were applied to the skin. A nonsterile conductive gel was applied to the face of the transducer. The operator wore sterile gloves and applied a sterile cover to the transducer. Before and after each procedure, the ultrasound apparatus was appropriately cleaned and disinfected with disinfectant wipes and allowed to air dry. A 12.5-MHz linear probe was positioned in the midaxillary line at the level of T5, and an in-plane needle was inserted into the fascia between the latissimus dorsi and serratus anterior muscles for ropivacaine (20 mL of 0.375%) injection. The injection for PECS I was performed in the fascia between minor and major pectoral muscles using 10 mL of 0.375% ropivacaine 8,11 . Needle position was confirmed using visualization of the separation of the layers with dispersion of the injected volume.
ELISA. Blood samples were collected in EDTA-Vacutainer tubes and processed by the Biobanco unit from the Hospital Sirio Libanes. Blood was immediately placed on ice and centrifuged. The plasma was separated and stored at −80 °C until measurement. IL-1beta, IL-6 and IL-10 concentrations in samples were measured in duplicate using specific commercial enzyme-linked immunosorbent assay (ELISA) kits (R&D Systems). The ELISA protocol was performed according to the manufacturer's specifications.

Study design.
Consenting patients were interviewed on the day of surgery, and the SF-36, DN4 and VAS scales were used. A blood sample was collected before to surgery. Anesthesia was performed according to group randomization (general anesthesia only or general anesthesia associated with SAM + PECS I), and the consumptions of fentanyl, propofol, cisatracurium and rocuronium were recorded. Patients were admitted to the post-anesthetic care unit (PACU) after surgery, and the following parameters were measured: time spent in PACU, VAS, PCA-morphine consumption, side effects and complications. Blood samples were collected 24 h after surgery, and VAS, PCA-morphine consumption, side effects and complications were assessed. Blood samples were evaluated in the ELISA assay to determinate the cytokine levels.
Duration of the study. The surgeries were performed from December 2015 to June 2016.
Breaking the codes. At the end of the study, the sponsor of the study had permission to release the code break envelopes/randomization list. These information codes were broken once the trial database was completed.
Data availability. The datasets generated and/or analyzed during the current study are available from the corresponding author upon reasonable request in the REDCap database (https://redcap.iephsl.org.br).
Sample size justification and statistical analysis. The sample size was calculated using www.openepi. com based on the results of Wu, who evaluated general anesthesia plus paravertebral versus general anesthesia block and produced an effect size of 1.5 for VAS 46 . Sixteen patients per group were required to achieve significant results with an alpha of 0.05 and a beta of 90%. There are no previous data on general anesthesia versus SAM + PECS I. Therefore, we estimated that 50 patients divided into two arms would be sufficient to show an effect of regional anesthesia versus general anesthesia.
Data are shown as the means ± standard deviation and Elisa data are shown in mean ± standard error. Demographic data, quality of life, drug consumption and time spent in the PACU were analyzed using the Mann-Whitney test. VAS and opioid consumption were analyzed using two-way ANOVA repeated measures (Factor 1: group, Factor 2: time) followed by Newman-Keuls post-hoc tests. The interleukin data were analyzed using the Wilcoxon test. Medication and side effects were analyzed using Cochran's Q test. Significance was set at P ≤ 0.05.