A Prospective CohorT Study of HandX - Assisted ENdoscopic MAstectomy: Feasibility and Safety (ATHENA I Study)

This is a prospective, single-center, single-arm interventional study designed to evaluate the feasibility and surgical safety of HandX-assisted endoscopic nipple-sparing mastectomy with immediate implant-based breast reconstruction. The HandX system is a handheld articulating robotic instrument that provides wrist-like motion, motion scaling, and ergonomic control. Unlike console-based robotic platforms, HandX integrates into standard minimally invasive workflows without the need for a large footprint, dedicated console, or complex docking procedures. Early clinical experience in other surgical specialties suggests that the technology may improve access and ergonomics during dissection while maintaining procedural efficiency. This study investigates its use specifically in endoscopic breast surgery, where instrument articulation and visualization are key technical challenges.

All participants will undergo the mastectomy through a single lateral mammary fold incision. Following tumescent injection and creation of a working space, a single-port device is placed, and CO₂ insufflation is used to establish the operative cavity. The HandX device is then employed for endoscopic dissection of the breast gland from the skin envelope and the nipple-areola complex. Specimen retrieval is performed through the same incision. Reconstruction is completed using implant-based techniques (prepectoral, dual-plane, PU-coated, or subpectoral), according to preoperative planning and standard practice. Axillary procedures (sentinel lymph node biopsy or axillary lymph node dissection) may be performed through the same incision when indicated.

The study focuses on technical feasibility-specifically, the ability to complete the endoscopic mastectomy using the HandX platform without unplanned conversion to an open approach. Technical success is defined in the protocol and includes completion of all key steps of the planned minimally invasive procedure. Adjunct use of standard laparoscopic instruments or minor incision extensions for specimen handling does not constitute conversion, provided that the minimally invasive workflow is preserved.

Safety outcomes include intraoperative complications, 30-day and 90-day postoperative adverse events, surgical site infections assessed according to CDC/NHSN definitions, implant-related complications, and implant loss through one year. Postoperative care follows standardized pathways for implant-based reconstruction, including consistent antibiotic and VTE prophylaxis policies and predefined criteria for drain management. Participants are reviewed at scheduled visits through postoperative day 28, with additional follow-up through day 90 for infection surveillance, and through one year for implant-related outcomes.

Patient-reported outcomes are assessed using the BREAST-Q® Reconstruction Module (Version 2.0), administered preoperatively and at postoperative months 1, 6, and 12. These measures provide data on satisfaction with breasts, psychosocial and sexual well-being, physical well-being of the chest, and satisfaction with aspects of care. Only implant-reconstruction-relevant scales are used.

All data are collected in electronic case report forms, stored securely, and managed in compliance with GDPR and institutional policies. Monitoring is internal due to the single-center pilot nature of the study.

The study plans to accrue up to 20 mastectomy cases, corresponding to approximately 15 participants, as bilateral procedures are counted per breast. The sample size of 20 cases is consistent with recommendations for feasibility studies intended to inform future multicenter comparative trials. Analyses are descriptive. Technical success, complication rates, and patient-reported outcomes will be summarized with confidence intervals. Progression criteria and stopping rules are predefined in the protocol, including thresholds for major complications, device-related serious events, and oncologic or surgical concerns that may warrant pause or termination of the study.

Findings from this pilot study will inform the development of larger controlled trials evaluating the comparative effectiveness, aesthetic outcomes, recovery profiles, and cost implications of HandX-assisted endoscopic mastectomy relative to other surgical approaches.

Inclusion criteria

• Female sex
• Age ≥ 18 years old
• Indication for therapeutic or prophylactic (risk-reducing) mastectomy for:

• early invasive breast cancer (Clinical Stage I-II at diagnosis) undergoing primary surgery
• early invasive breast cancer (Clinical Stage I-II at diagnosis) undergoing surgery post systemic (neoadjuvant) therapy with clinical evidence of partial or complete response
• ductal carcinoma in situ (DCIS), or
• BRCA or other breast cancer - related genetic mutation carriers, or
• high risk for development of breast cancer.
• Breast volume: cup sizes A to C as defined by underwear size, expected implant volume <550cc and glandular ptosis not exceeding Grade I Regnault's classification.
• ECOG / WHO Performance Status <2
• Subject with signed and dated informed consent form

Exclusion criteria

• Chest wall or skin invasion
• Extended lymph node involvement at diagnosis (cN2)
• Inflammatory breast cancer
• Tumor distance from nipple - areola complex <1cm on imaging studies
• Active smoking/nicotine use within 4 weeks pre-op (combustible tobacco, vaping, nicotine pouches, NRT)
• BMI >35
• High risk patients with severe and poorly controlled co-morbid conditions (including but not limited to diabetes, heart disease, renal failure or liver dysfunction)
• Pregnancy or breastfeeding
• Psychiatric, addictive, or any disorders which compromise the ability to give informed consent for participation in this study
• Subject without signed and dated informed consent form