Role of Axillary Lymph Node Dissection for Residual MACROMETASTASES After NEOADJUVANT Chemotherapy in Patients With HER2+ and Triple Negative Breast Cancer: The OPBC-11/MACRONAC Study (MACRONAC)

May 18, 2026 updated by: University Hospital, Basel, Switzerland
In this multicenter retrospective cohort study the aim is to determine the safety of omission of axillary lymph node dissection in patients with TNBC and HER2+ tumors with residual macrometastases (in the SLN/TAD/TAS or MARI node) after NAC.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Observational

Enrollment (Estimated)

600

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: Walter P. Weber, Prof. Dr. med.
  • Phone Number: +41 61 328 61 49
  • Email: walter.weber@usb.ch

Study Contact Backup

Study Locations

  • Switzerland
      • Basel, Switzerland, 4031
        • Recruiting
        • Department Breast, Abdomen, Pelvis; Universitätsspital Basel
        • Contact:
        • 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

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Patients who presented with cT1-4 N0-3 TNBC (including ER-low tumors) or HER2+ BC who underwent NAC followed by axillary staging with either SLN surgery, TAD, TAS or the MARI procedure and were found to have residual macrometastases will be included. Data from "Universitätsspital Basel" will be extracted from medical records of from an already existing database.

Description

Inclusion Criteria:

  • Women and men with a diagnosis of stage I-III TNBC or HER2+ breast cancer at diagnosis. HER2+ is defined as an Immunohistochemistry (IHC) score of 3+ or positive FISH. TNBC is defined as ER and Progesterone Receptor (PR) IHC expression of 0 and HER2 negativity defined as either IHC expression of 0-1+ or lack of gene amplification (FISH < 2.0). Patients with ER low (1-10%) and/or PR low (1-10%) tumors are allowed.
  • Any histological subtype
  • For Clinical Nodal Stage (cN) 0 at presentation: any axillary staging technique including palpation with or without imaging is allowed. Dual tracer mapping is not required for SLN surgery.
  • For cN+ at presentation: Percutaneous biopsy proven confirmation is required at diagnosis. Staging techniques after NAC include: SLN surgery with dual mapping or Targeted Axillary Dissection (TAD: imaging-guided localization of sampled node in combination with SLN procedure with or without dual mapping) or Tailored Axillary Surgery (TAS: removal of the sentinel lymph nodes as well as selective removal of all palpable disease and documentation of the removal of the initially biopsy-proven and clipped lymph node metastasis by specimen radiography) or the MARI procedure (Marking Axillary Lymph Nodes with Iodine Seeds).
  • Received neoadjuvant chemotherapy
  • Residual macrometastases (metastasis greater than 2 mm in diameter) detected on SLN surgery or TAD ot TAS or MARI (on frozen section or final pathology)
  • Concomitant presence of Isolated Tumor Cells (ITCs) and micrometastases in other sentinel lymph nodes is allowed
  • Following SLN surgery/TAD/TAS/MARI patients underwent completion ALND, nodal radiation therapy (RT), both or no further axillary treatment
  • At least 1-year follow-up (had surgery at any time point until October 2024 at the latest) - Prior history of ductal carcinoma in situ (DCIS) is allowed

Exclusion Criteria:

  • Did not undergo SLN surgery/TAD/TAS/MARI (e.g., went straight to ALND)
  • Presence of ITCs or micrometastases alone in the sentinel nodes (or TAD nodes or MARI node or TAS nodes) without macrometastases
  • HR+HER2- tumors (except ER low and or PR-low)
  • Stage IV disease at presentation
  • Inflammatory breast cancer at presentation
  • Neoadjuvant endocrine therapy
  • Macrometastases detected by Oncoplastic Breast Consortium (OSNA)

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

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Axillary lymph node dissection (ALND) cohort
Other: Data Collection from medical records of from an already existing database "ONCOLOGICAL BREAST SURGERY DATABASE OF THE UNIVERSITY HOSPITAL OF BASEL" which was initiated in 2016.
All trial data are/ have been collected within the clinical routine between 2013 and October 2024. All data will be analyzed descriptively using adequate statistical measures and plots. Clinico-pathological characteristics will be compared between patients treated with and without ALND. Depending on the median follow-up of both cohorts (ALND, no ALND) the 3-year cumulative incidence rates will be compared between ALND and no ALND.
No Axillary lymph node dissection (ALND) cohort
Other: Data Collection from medical records of from an already existing database "ONCOLOGICAL BREAST SURGERY DATABASE OF THE UNIVERSITY HOSPITAL OF BASEL" which was initiated in 2016.
All trial data are/ have been collected within the clinical routine between 2013 and October 2024. All data will be analyzed descriptively using adequate statistical measures and plots. Clinico-pathological characteristics will be compared between patients treated with and without ALND. Depending on the median follow-up of both cohorts (ALND, no ALND) the 3-year cumulative incidence rates will be compared between ALND and no ALND.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
3-year rate of any axillary recurrence
Time Frame: 3-year follow-up after diagnosis of stage I-III TNBC or HER2+ breast cancer and SLN surgery/TAD/TAS/MARI
3-year rate of any axillary recurrence (defined as isolated or combined with local or distant recurrence) in patients with residual macrometastases after NAC overall and by use of axillary dissection.
3-year follow-up after diagnosis of stage I-III TNBC or HER2+ breast cancer and SLN surgery/TAD/TAS/MARI

Collaborators and Investigators

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

Sponsor

University Hospital, Basel, Switzerland

Investigators

  • Principal Investigator: Walter P. Weber, Prof. Dr. med., Department Breast, Abdomen, Pelvis
  • Study Director: Giacomo Montagna, MD MPH, Breast Service, Department of Surgery; Memorial Sloan Kettering Cancer Center

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)

February 1, 2026

Primary Completion (Estimated)

December 1, 2027

Study Completion (Estimated)

December 1, 2027

Study Registration Dates

First Submitted

April 16, 2026

First Submitted That Met QC Criteria

April 16, 2026

First Posted (Actual)

April 23, 2026

Study Record Updates

Last Update Posted (Actual)

May 19, 2026

Last Update Submitted That Met QC Criteria

May 18, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2026-00317 bb26Weber2

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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