Single-Port Robotic-assisted Transaxillary Breast-conserving Surgery: A Prospective, Single-arm, Non-randomized Phase IIa Clinical Trial

Summary

This prospective study evaluated the implementation of a novel, single-port, robotic platform in oncoplastic breast-conserving surgery for malignant lesions. The primary endpoint focused on technical success, defined as the achievement of tumor-free resection margins confirmed by intraoperative frozen-section histopathology, with secondary assessment of aesthetic outcomes and life quality score of patients.

Abstract

The integration of robotic platforms in breast oncology has witnessed substantial expansion, fueled by their inherent advantages in minimally invasive access and enhanced intraoperative maneuverability. Most of the robotic-assisted breast surgery has been performed using multi-arm robots. However, the implementation of single-port robotic (SPr) systems in mammary interventions continues to undergo rigorous clinical evaluation, particularly regarding long-term oncological safety and cost-effectiveness metrics. Notably, multi-arm robotic systems demonstrate constrained operability in the restricted mammary workspace, whereas the transaxillary, single-port approach demonstrates enhanced spatial adaptability, achieving more optimal instrument articulation in confined surgical fields while concurrently optimizing aesthetic outcomes through precise subcutaneous tissue dissection. The study (ClinicalTrials.gov ID: NCT06738654) constituted a prospective, single-arm, non-randomized trial for primary exploration of feasibility and safety regarding a single-port robotic system in breast-conserving surgery (BCS) in six patients with early-stage breast cancer undergoing transaxillary, SPr-assisted, partial mastectomy with sentinel lymph node biopsy (SLNB). A total of 6 patients from Daping Hospital (Army Medical Center) between December 2024 and February 2025 were included in this study, with the first successful implementation performed on December 24, 2024. Intraoperative frozen-section histopathology confirmed negative resection margins in all patients, meeting the criteria for surgical success. The mean operative time was 232 min, with an average postoperative drainage volume of 250 mL. The axillary drainage tubes remained for an average of 10 days; the mean hospital stay was 10 days. Quality of life assessment through FACT-B demonstrated satisfaction scores. The six cases demonstrate the procedural safety and oncological feasibility of transaxillary SPr-assisted BCS within minimally invasive breast oncology. Mechanistically, the axillary portal approach achieves scar containment through only one incision in the inframammary fold, while preserving the native breast architecture. This technique significantly improves postoperative quality of life metrics through precise subcutaneous fascia preservation, reducing psycho-emotional distress associated with visible scarring. The technical paradigm aligns with oncoplastic principles by reconciling radical tumor excision with contemporary aesthetic demands in breast cancer candidates.

Introduction

Globally ranking as the second most prevalent malignancy (11.6% of new cancer diagnoses), breast cancer demonstrates an escalating incidence with earlier onset patterns^1,2. Surgery remains the primary treatment for breast cancer. The historical trajectory of breast cancer surgery has been characterized by the emergence of multiple surgical techniques. This evolution spans from Halsted's radical mastectomy in 1882 to the emergence of BCS in the 1980s. Breast cancer is not merely a localized disease confined to the breast, representing rather a systemic illness. While surgery remains unavoidable, BCS outperforms mastectomy in early-stage survival outcomes³, yet resultant scarring poses particular challenges for Chinese women aged <50 years -- a demographic characterized by denser breast parenchyma and increased scar susceptibility relative to Caucasians⁴. Consequently, advancing minimally invasive surgical approaches becomes essential for reconciling oncological safety with aesthetic preservation in this population.

Compared to traditional BCS, minimally invasive approaches provide equivalent oncological efficacy in tumor removal, alongside enhanced wound recovery and diminished postoperative discomfort⁵. Robotic technology, owing to its unique advantages, has been extensively adopted in various surgical disciplines, including urology^6,7, gynecology, and general surgery^8,9. Robot-assisted, minimally invasive procedures also have demonstrated reduced intraoperative blood loss, lower rates of postoperative complications, enhanced preservation of limb function, and improved satisfaction with cosmetic outcomes. Statistical evidence from research reveals that traditional BCS carries a postoperative complication rate of 7%, while robotic-assisted surgery demonstrates a substantially lower rate of 3.9%^10,11,12. Robotic technology has advanced surgical practices by facilitating remote, digital, and intelligent capabilities and delivers a three-dimensional, high-definition, visual interface with substantial magnification, providing surgeons with superior visualization, heightened precision, and enhanced procedural control. Robotic systems are equipped with wristed instruments that offer 540° rotational capability, allowing for intuitive motion and enhanced precision in delicate tasks. Such technological advancements are especially vital in breast surgery, which frequently involves navigating narrow and restricted anatomical spaces.

Toesca et al.¹³ initiated robotic-assisted breast surgery with the formal use of robotic technology. Subsequently, robotic systems in breast surgery developed significantly^14,15,16. In clinical implementation, multi-port robotic systems face significant spatial constraints in the limited operative field of breast surgery. The limited space restricts movement, causes collisions, and weakens robotic advantages. The development of the SPr system has successfully mitigated the disadvantages. Such as wristed instruments and high-definition magnification attributes render them particularly effective for executing precise surgical tasks within restricted operative spaces. BCS is widely recognized for its superior aesthetic results, positive impact on patients' quality of life, and proven oncological efficacy, all of which contribute to its status as a standard therapeutic approach^17,18,19,20.

This trial adopted a single-arm, non-randomized phase IIa clinical study design based on Simon's two-stage methodology. The inclusion crtieria were (1) high aesthetic requirement, (2) no prior chest surgery/radiotherapy, (3) no anesthesia contraindications, (4) early stage, (5) preoperatively qualified for BCS. Patients were excluded based on (1) diffuse malignant calcification, (2) persistent positive margins after resection, or (3) patient refusal.

Protocol

Ethical clearance for this study was granted by the Ethics Committee of the Army Medical Center, and the trial is officially registered on ClinicalTrials.gov with a unique identifier (NCT06738654). Six patients with early-stage breast cancer undergoing transaxillary, SPr-assisted, partial mastectomy with sentinel lymph node biopsy (SLNB) were enrolled at the Army Medical Center (IRB approval No. 341[2024]). Written informed consent was secured from all participants before their enrollment in the study. All anesthesia-related supplies have been used under the direct supervision of licensed anesthesiologists, with real-time documentation of drug administration and waste disposal. Sharps have been segregated into puncture-resistant containers labeled with biohazard symbols, while hazardous chemicals have been stored in designated cabinets with GHS-compliant labels and Safety Data Sheet (SDS) accessibility. All containers displayed clear safety warnings in accordance with national and international regulations.

1. Preoperative preparation

1. Perform ultrasound-guided localization to demarcate tumor margins and extended resection boundaries. Create a 3 cm preoperative incision mark along the axillary fold on the operative side (Figure 1).
2. Position the patient supine with the arm abducted to 90° (Figure 2).
3. Commence surgical site disinfection post completion of nasal intubation, anesthetic delivery (Ropivacaine 30 mL, erector spinae plane block; Cisatracurium Besilate 14 mg, i.v.; Etomidate Emulsion 20 mg, i.v.; Midazolam 2 mg, i.v.; Sufentanil 35 µg, i.v.), and bladder catheterization. Then, encase the disinfected operative-side upper extremity in sterile towels and position on the arm board with secure fixation.
   NOTE: Disinfection boundaries: Superior: mandibular border. Inferior: nipple plane horizontal. Contralateral limit: anterior axillary line. Operative-side limit: Posterior axillary line with elbow joint inclusion.
4. Apply small sterile drapes in a clockwise sequence encompassing the inferior surgical field, contralateral side, cephalad region, and operative side, followed by layering medium drapes beginning caudally and extending cephalad, then conclude draping with a 10 cm x 10 cm operative field (Figure 3).

2. Surgical procedure

NOTE: The surgical procedure is not differentiated based on the tumor location in different quadrants and is universally applicable.

1. Inject 2 mL of methylene blue vertically into the subcutaneous layer (depth: 0.5 cm ± 0.1 cm) at multiple periareolar sites, creating a chromatic mapping grid for intraoperative axillary node identification.
2. Make an incision along the marked axillary crease using a scalpel, sequentially dividing the cutaneous and subcutaneous tissues, then track the dyed lymphatic channels to locate the stained sentinel node, dissect the axillary adipose and connective tissues through combined blunt and sharp techniques, excise the identified sentinel node, and immediately submit the specimen for frozen section analysis.
3. Following the return of the axillary sentinel lymph node frozen pathology report, proceed with axillary lymph node dissection immediately if metastatic involvement is detected.
4. After exposing the lateral edge of the pectoralis major via the axillary incision, separate the retromammary fascial plane, extending 1-2 cm beyond the intended resection area. Demarcate the medial resection boundary near the areola with two methylene blue marks, while marking the lateral boundary with one. Label both the superior and inferior margins with a single methylene blue point (depth 1-2 cm).
5. Administer tumescent fluid (250 mL of saline, 2 vials of lidocaine, 2 vials of ropivacaine, 1 vial of epinephrine) subcutaneously over the gland. Dissect the breast's superficial fascial plane with thoracic scissors using alternating blunt and sharp dissection, ensuring a 1-2 cm extension beyond the planned resection area. Blot fluid from the dissected space using large gauze, then deploy a wound retractor via the axillary incision (Figure 4).
6. Connect the insufflator and set the insufflation pressure to 8 mmHg with a flow rate of 20 L/min to establish pneumoperitoneum.
7. Upon establishing visualization via the SPr camera, proceed along the pectoralis major's lateral border to access retropectoral tissue. Confirm the dissection limits by palpation, and extend the retromammary dissection 1-2 cm beyond the target area, anchoring the boundaries with 10 syringe needle markers (Figure 5). Deploy the single-port robotic monopolar scissors and bipolar forceps, enter the resection zone through the superficial fascial layer, and execute vertical lateral resection from superior to inferior. Extend the resection bilaterally to complete cylindrical gland removal, then deactivate and remove all robotic components.
8. Retrieve the specimen and mark two methylene blue-stained points as the medial boundary, one point as the lateral boundary. Orient the specimen to distinguish superior/inferior, deep (basal), and superficial surfaces with corresponding labels. Inspect the specimen grossly to confirm tumor presence, photograph the lesion with anatomical orientation markers, and submit the specimen for pathological evaluation.
9. Reglove and irrigate the surgical field. Achieve hemostasis using electrocautery. Place a negative-pressure drain anterior to the pectoralis major, exteriorize it through the incision, and secure with sutures. Upon completing layered closure (subcutaneous tension-reducing + skin absorbable sutures), verify drain functionality and nipple perfusion before final sterile dressing application.

Results

The mean operative time for the six patients was 232 min (min: 180 min, max: 295 min), and the mean intraoperative blood loss was 15 mL (min: 10 mL, max: 30 mL). The average postoperative drainage volume was 250 mL (min: 100 mL, max: 470 mL). The axillary drainage tubes remained for an average of 10 days (min: 4 days, max: 17 days). The mean hospital stay was 10 days (min: 8 days, max: 16 days), with the longest stay attributed to postoperative breast hematoma.

Three of the six patients underw...

Discussion

The successful execution of single-port, robotic-assisted, partial mastectomy via axillary approach in six patients underscores the viability of SPr systems for BCS, with the first successful implementation performed on December 24, 2024. The critical surgical techniques involve prerobotic docking cavity creation and delineation of extended resection margins in BCS. Optimal cavity creation minimizes instrumental access challenges imposed by anatomical constraints while maximizing surgical field exposure. Intraoperative f...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Bipolar coagulating forceps	Edge Medical,CHINA	SP1000	Mian surgery instrument ___
Cisatracurium Besilate Injection	NanJing JIAN YOU, CHIINA	___	Anesthetic drug 5 mL, 10 mg
Disposable multi-channel single-port laparoscopic trocar	SHIAIDE XIAMEN,CHINA	20240708006	Connect the robot II A, 4E-70 x 150
Epinephrine Hydrochloride Injection	DIKANG CHONGQING,CHINA	___	Decrease blood 1 mL, 1 mg
Etomidate Injectable Emulsion	Jiangsu Nhwa Pharmaceutical Co, CHINA	___	Anesthetic drugV 10 mL
Lidocaine Hydrochloride Injection	TIANSHENG HUBEI,CHINA	___	Decrease blood 5 mL, 0.1 g
Methylthioninum Chloride	JUMPCAN PHARMACEUTICAL GROUP CO.LTD	___	Dying 2 mL, 20 mg
Midazolam Injection	Jiangsu Nhwa Pharmaceutical Co, CHINA	___	Anesthetic drug 10 mg
Monopolar electric scissors	Edge Medical,CHINA	SP1000	Mian surgery instrument ___
Negative pressure drainage bottle	B.Braun,Germany	5523443	Drainage ___
Ropivacaine Hydrochloride Injection	JIABO GUANGDONG,CHINA	___	Decrease blood 10 mL, 100 mg
Rubber gloves	YADU Medical,CHINA	___	Connect the robot 7.5
Single-Port Laparoscopic Surgical Robot	Edge Medical,CHINA	SP1000	Mian surgery instrument JingFeng Single-Port Laparoscopic Surgical Robot SP1000
Sodium Chloride Injection	HUALU SHANDONG,CHINA	___	Prepare the solution in proportion 100 mL, 0.9%
Sufentanil Citrate Injection	RenFU Medical, CHINA	___	Anesthetic drug 1 mL, 50 μg
Synthetic suture	Covidien,American	___	Close the wound 4-0/GL181 or 4-0/GL34MG
Syringe	DONGBEI Medical,CHINA	___	Limit the boundary 10 mL