The Comparison Between M-E-BCS and C-O-BCS. (MECO)

April 13, 2026 updated by: Du Zhenggui

A Comparative Study of Minimal Accessory-Incision-Assisted Endoscopic Breast-Conserving Surgery With Minimal Auxiliary Incisions Versus Conventional Open Breast-Conserving Surgery: A National Multicenter, Open-Label, Randomized Controlled Trial (MECO-BCS)

This study is a multicenter, open-label, randomized controlled trial. The study aims to evaluate differences in operative efficiency (e.g., operative time), economic effect, surgical safety (e.g., surgical complication rates), postoperative aesthetics (e.g., BREAST-Q scores, Harris scores, SCAR-Q scores and Ueda scores), and oncological safety (e.g., margin status, no local recurrence survival) between patients undergoing M-E-BCS and patients undergoing C-O-BCS.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Breast cancer is a highly prevalent malignant tumor among women, and comprehensive treatment mainly based on surgery is the main mode. Breast aesthetics is important, breast-conserving surgery (BCS) is a common surgical approach, which can preserve the breast shape, does not affect subsequent treatment, and has been confirmed to be safe in terms of oncology. Conventional open breast-conserving surgery (C-O-BCS) requires multiple incisions, resulting in prominent scars. With the introduction of minimally invasive techniques, endoscopic breast-conserving surgery (E-BCS) has emerged as an alternative. It reduces the number of incisions, lowers the incidence of complications, and enhances aesthetic outcomes and patient satisfaction, while maintaining similar oncological safety compared to open surgery. However, single-incision E-BCS is limited by restricted operative space, making precise tumor resection and oncoplastic procedures challenging. Although multi-incision E-BCS facilitates surgical procedures, it does not improve scar aesthetics and may increase surgical trauma and costs. As a result, the adoption of endoscopic breast-conserving surgery has been limited, and there is a lack of high-quality clinical studies in this area.

Our team proposed the minimal accessory-incision-assisted endoscopic breast-conserving surgery (M-E-BCS), which has concealed incisions, strong operability, and good cosmetic effects. It is being popularized in China. To comprehensively evaluate its clinical benefits, large-scale multicenter studies are needed to provide evidence-based medical evidence and optimize surgical plans.

Therefore, this national multicenter, open-label, randomized controlled trial will compare outcomes between patients undergoing M-E-BCS versus C-O-BCS. The study aims to evaluate differences in operative efficiency (e.g., operative time), economic effect, surgical safety (e.g., surgical complication rates), postoperative aesthetics (e.g., BREAST-Q scores, Harris scores, SCAR-Q scores and Ueda scores), and oncological safety (e.g., margin status, no local recurrence survival).

Study Type

Interventional

Enrollment (Estimated)

1366

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

  • Name: Zhenggui Du Du
  • Phone Number: +86 13880768222
  • Email: docduzg@163.com

Study Locations

  • China
    • Sichuan
      • Chengdu, Sichuan, China, 610000
        • West China Hospital of Sichuan University
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • female patients aged 18-70 years (inclusive);
  • preoperative pathological examination confirmed it as invasive breast cancer or ductal carcinoma in situ;
  • both clinical and imaging examinations clearly indicated that the lesion was a single lesion confined within the gland, without invasion of the skin, subcutaneous tissue, pectoralis major muscle, or the nipple-areola complex;
  • tumors in the inner and outer quadrants (three classification method, as shown in Figure 2);
  • preoperative tumor size ≤3 cm (pre-neoadjuvant chemotherapy if applicable);
  • the tumor is more than 2 cm away from the nipple (the distance is based on physical examination, with MRI and ultrasound as supplementary methods);
  • the patient has a clear intention to preserve the breast and can receive standard radiotherapy after the operation;
  • voluntary provision of informed consent. .

Exclusion Criteria:

  • clinically or radiologically evaluated as multifocal or multicentric breast cancer, with diffuse suspicious calcification, long spiculated masses, extensive local resection unable to obtain sufficient negative margins or ideal shape;
  • persistent positive tumor margins, and resection cannot ensure negative margins after resection;
  • inflammatory breast cancer;
  • pregnant and lactating women;
  • previous history of breast cancer surgery (including patients with recurrence after ipsilateral breast-conserving surgery);
  • breast cancer genetic gene mutations (such as BRCA1/2 gene mutations);
  • preoperative severe underlying diseases that cannot tolerate general anesthesia and surgical procedures.
  • other situations that the researchers consider unsuitable for participation

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Intervention group
Minimal accessory-incision-assisted endoscopic breast-conserving surgery
Procedure: Minimal accessory-incision-assisted endoscopic breast-conserving surgery
A small incision was made in the concealed area of the armpit, and a endoscopic device was inserted. Under direct vision, the tumor was precisely removed and the lymph nodes in the armpit were cleared layer by layer. The incision was then sutured layer by layer, and a drainage tube was placed after the operation.
Experimental: Control group
Conventional open breast-conserving surgery
Procedure: Conventional open breast-conserving surgery
Conventional open breast-conserving surgery is a surgical approach that aims to preserve the appearance and function of the breast as much as possible while ensuring the complete removal of the tumor. It is suitable for eligible patients with early-stage breast cancer and requires comprehensive postoperative treatment measures such as radiotherapy.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Local recurrence rates
Time Frame: Postoperative 5 years
The risk of local recurrence within five years.
Postoperative 5 years

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Resection mastectomy weight
Time Frame: Immediate postoperative
Mean mastectomy weight (g)
Immediate postoperative
Surgical efficiency
Time Frame: Intraoperative
Total operative time (min) from skin incision to complete closure of incision, the operative time for axillary surgery and the operative time for breast surgery.
Intraoperative
Economic effect
Time Frame: 1 month postoperative
The total cost from the patient's admission to discharge, the surgery fee and the hospitalization fee (USD).
1 month postoperative
Surgical safety
Time Frame: Intraoperative, 3 months postoperative.
Surgical complication rates, major complication rates and minor complication rates, including flap scald, NAC ischemia/necrosis, seroma, surgical area infection, bleeding, incision splitting, flap ischemia/necrosis.
Intraoperative, 3 months postoperative.
Aesthetic outcomes (BREAST-Q score)
Time Frame: Preoperative, 6 months postoperative, 2 years postoperative and 5 years postoperative.
The BREAST-Q scores range from 0 to 100, with higher scores indicating better outcomes. Both raw questionnaire scores and standardized transformed scores will be documented, along with pre- to postoperative differences in transformed scores.
Preoperative, 6 months postoperative, 2 years postoperative and 5 years postoperative.
Aesthetic outcome (Harris score)
Time Frame: Preoperative, 6 months postoperative, 2 years postoperative and 5 years postoperative.
The Harris score was used to record the subjective judgment of symmetry of the reconstructed breast compared to the contralateral breast. The results were categorized as excellent (treated breast nearly identical to untreated breast), good (treated breast slightly different than untreated), fair (treated breast clearly different than untreated), and poor (treated breast seriously distorted).
Preoperative, 6 months postoperative, 2 years postoperative and 5 years postoperative.
Aesthetic outcome (Ueda score)
Time Frame: Preoperative, 6 months postoperative, 2 years postoperative and 5 years postoperative.
Doctor-reported aesthetic outcomes will be evaluated by three professional breast surgeons using the Ueda scale, based on postoperative photographs. Scores range from 0 to 10 points, with higher values indicating better results. The categorized as follows: Excellent (≥9 points), Good (7-8 points), Fair (5-6 points), Poor (≤4 points). Both raw scores and categorizations will be documented.
Preoperative, 6 months postoperative, 2 years postoperative and 5 years postoperative.
Aesthetic outcome (SCAR-Q score)
Time Frame: Preoperative, 6 months postoperative, 2 years postoperative and 5 years postoperative.
A validated scar-specific patient-reported outcome measure tool for assessing the quality of life of patients with scars. It consists of three independent scales: scar appearance, scar symptoms, and psychosocial impact. Transformed scores range from 0 to 100, with higher scores indicating better outcomes.
Preoperative, 6 months postoperative, 2 years postoperative and 5 years postoperative.
Surgical margin involvement
Time Frame: 2-3 weeks postoperative after paraffin-embedded pathological report available.
Surgical margin involvement was defined as ink on tumor on postoperative paraffin-embedded pathological examination.
2-3 weeks postoperative after paraffin-embedded pathological report available.
Local Recurrence-Free Survival(LRFS)
Time Frame: 2 years postoperative and 5 years postoperative.
The time interval from initiation of treatment to the first recurrence at the primary tumor site. If local recurrence appears, record the time and location of recurrence.
2 years postoperative and 5 years postoperative.
Regional Recurrence-Free Survival (RRFS)
Time Frame: 2 years postoperative and 5 years postoperative.
The time from the date of diagnosis or treatment to the date of first regional recurrence (recurrence in the ipsilateral regional lymph nodes, including axillary, internal mammary, or supraclavicular nodes) or death from any cause, whichever occurs first.
2 years postoperative and 5 years postoperative.
Distant Metastasis-Free Survival (DMFS)
Time Frame: 2 years postoperative and 5 years postoperative.
The time from the date of diagnosis or treatment to the date of first distant metastasis (spread to distant organs such as bone, lung, liver, or brain) or death from any cause, whichever occurs first.
2 years postoperative and 5 years postoperative.
Progression-Free Survival (PFS)
Time Frame: 2 years postoperative and 5 years postoperative.
The time from the date of initiation of systemic therapy (or randomization in clinical trials) to the date of first documented disease progression (either local, regional, or distant recurrence) or death from any cause, whichever occurs first.
2 years postoperative and 5 years postoperative.
Disease-Free Survival(DFS)
Time Frame: 2 years postoperative and 5 years postoperative.
The period from treatment initiation to any disease recurrence (local, regional, or distant) or death.If above event appears, record the time and disease location.
2 years postoperative and 5 years postoperative.
Breast Cancer-Specific Survival (BCSS)
Time Frame: 2 years postoperative and 5 years postoperative.
The time from the date of diagnosis to the date of death specifically attributed to breast cancer. Deaths from other causes are considered competing events and are censored.
2 years postoperative and 5 years postoperative.
Overall Survival(OS)
Time Frame: 2 years postoperative and 5 years postoperative.
The time from treatment initiation (or diagnosis) to death from any cause. If death appears, record the time and reason.
2 years postoperative and 5 years postoperative.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Du Zhenggui

Collaborators

West China Second University Hospital
Suzhou Municipal Hospital
Taiyuan Central Hospital of Shanxi Medical University
Chengdu Second people's hospital
The Fourth People's Hospital of Sichuan Province
West China Fourth Hospital of Sichuan University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

April 1, 2026

Primary Completion (Estimated)

December 1, 2032

Study Completion (Estimated)

December 31, 2032

Study Registration Dates

First Submitted

March 15, 2026

First Submitted That Met QC Criteria

April 13, 2026

First Posted (Actual)

April 20, 2026

Study Record Updates

Last Update Posted (Actual)

April 20, 2026

Last Update Submitted That Met QC Criteria

April 13, 2026

Last Verified

July 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2025(1479)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Qualified researchers can request access to anonymized individual patient-level data via the request portal. All IPD requests should be emailed to Dr. Zhenggui Du, the general project leader, and will be evaluated by Dr. Du and the head of the collaborating organization to decide whether to approve.

IPD Sharing Time Frame

After publication of relevant research outputs, such as academic papers and books.

IPD Sharing Access Criteria

When a request has been approved, the investigator will provide access to the de-identified individual patient-level data in the data management platform (Electronic Data Capture, EDC). A signed Data Sharing Agreement (non-negotiable contract for data accessors) must be in place before accessing the requested information. Additionally, all users will need to accept the terms and conditions of the data management platform to gain access.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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