No Axillary Surgical Treatment in Clinically Lymph Node Negative Patients on Ultrasonography After Neoadjuvant Chemotherapy (Neo-NAUTILUS)

January 26, 2026 updated by: Wonshik Han, Seoul National University Hospital

No Axillary Surgical Treatment in Clinically Lymph Node Negative Patients on Ultrasonography After Neoadjuvant Chemotherapy: A Prospective, Phase III Clinical Trial

NEO-NAUTILUS is a prospective, multicenter, randomized phase III clinical trial to evaluate whether omitting axillary lymph node surgery (ALND or SLNB) in clinically lymph node-negative breast cancer patients after neoadjuvant chemotherapy is non-inferior to performing SLNB in terms of 5-year disease-free survival.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Background:

  • No prospective studies have proven that axillary lymph node surgery improves survival in breast cancer patients.
  • The ACOSOG Z0011 trial showed that additional axillary dissection did not improve recurrence or survival, even with a 23.7% incidence of non-sentinel node metastases.
  • NSABP B-32 established the oncologic safety of SLNB, significantly reducing complications like lymphedema compared to axillary dissection. However, SLNB still carries risks of lymphedema, sensory changes, seromas, and infections.
  • The trend has now shifted toward identifying candidates for omitting axillary surgery to minimize unnecessary complications.
  • The SOUND trial demonstrated non-inferiority of omitting SLNB in early-stage breast cancer patients with negative axillary ultrasound. Five-year distant metastasis-free survival was comparable between SLNB and no-SLNB groups (97.7% vs. 98.0%).
  • Improved ultrasound accuracy (e.g., FNR: 13.7% in SOUND; 11.3% in NAUTILUS) and the therapeutic contribution of whole-breast radiation likely support these findings.
  • Patients with a complete pathological response (pCR) in the breast post-NAC rarely have residual lymph node metastases, reducing the need for axillary surgery.
  • Single-arm studies (e.g., EUBREAST-01, ASICS, ASLAN) have explored omitting axillary surgery in patients with confirmed breast pCR. However, these studies face limitations due to small sample sizes, single-arm design, and the necessity of axillary surgery if pCR is not achieved.
  • To address these limitations, the NEO-NAUTILUS trial proposes the first randomized trial to compare disease-free survival and local recurrence rates between patients who omit SLNB (experimental group) and those who undergo SLNB (control group) after NAC, focusing on patients deemed axillary node-negative by ultrasound.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
464

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 3

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

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.
  • Name: Wonshik Han, MD, PhD.
  • Phone Number: 82-2-3461-6060
  • Email: hanw@snu.ac.kr

Study Locations

  • South Korea
      • Seoul, South Korea, 03080
        • Recruiting
        • Seoul National University Hopsital

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Women aged ≥19 years.
  • Histologically confirmed invasive breast carcinoma treated with neoadjuvant chemotherapy.
  • Clinical staging prior to NAC: cT1-3, cN0, M0 (AJCC 8th Edition).

  • If pre-NAC staging is cT1-3, cN1, M0, must meet the following criteria:

    1. HER2-positive or triple-negative breast cancer (TNBC).
    2. At least 30% reduction in tumor size on MRI after NAC (comparing pre- and post-NAC MRI).
  • Negative axillary lymph node status on ultrasound after NAC.
  • Planned for breast-conserving surgery with completed neoadjuvant chemotherapy (at least half the planned regimen must be completed).
  • ECOG performance status of 0-2.
  • Signed written informed consent before enrollment.

Exclusion Criteria:

  • History of any cancer within the past 5 years.
  • Bilateral breast cancer.
  • Patients requiring mastectomy.
  • Tumor size >5 cm after NAC.
  • Male breast cancer.
  • Pregnant or breastfeeding women.
  • Inability to understand and complete questionnaires.

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: Single

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: No SLNB group
The study arm - BCS without SLNB
Procedure: No axillary surgery
BCS only. Ommission of axillary surgery. No axillary surgery after neoadjuvant chemotherapy.
Other: SLNB group
The control arm - BCS with SLNB(+/-ALND)
Procedure: Axillary surgery
BCS with SLNB(+/-ALND)

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Invasive Disease Free Survival (iDFS)
Time Frame: 5 years
Evaluate invasive disease free survivals
5 years

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Overall Survival (OS)
Time Frame: 5 years
Evaluate overall survival
5 years
Distant Metastasis Free Survival (DMFS)
Time Frame: 5 years
Evaluate distant metastasis free survival
5 years
Axillary recurrence rate
Time Frame: 5 years
Evaluate ipsilateral axillary recurrence rate
5 years
Locoregional Recurrence Rate (LRR)
Time Frame: 5 years
Evaluate locoregional recurrence rate
5 years
QoL
Time Frame: 1 year
Evaluate Quality of Life of patient by EORTC QLQ-C30 questionnaire
1 year

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Seoul National University Hospital

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Asan Medical Center

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 (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
June 4, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 31, 2029

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 31, 2034

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
November 21, 2024

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 21, 2024

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
November 26, 2024

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
January 28, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 26, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
January 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • H-2410-138-1581

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Study protocol will be shared.

IPD Sharing Time Frame

The study protocol will be published as a journal article.

IPD Sharing Access Criteria

Anyone interested in viewing the study protocol will be able to access it through the published journal.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

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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