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

NCT07546695 | Active Not Recruiting

• 1 other identifier: 2026-00317 bb26Weber2
• Study Type: observational
• Target: 600
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Breast Cancer

Keywords

Axillary lymph node dissection (ALND); Triple Negative Breast Cancer (TNBC); Breast Conserving Surgery (BCS); Human Epidermal Growth Factor Receptor 2 Positive/ Negative (HER2+/- ); Hormone Receptor Positive/ Negative (HR+/-); Neoadjuvant Chemotherapy (NAC); Targeted Axillary Dissection (TAD); Tailored Axillary Surgery (TAS); Marking Axillary Lymph Nodes with Iodine Seeds (MARI); Sentinel Lymph Node (SLN)

Outcome Measures

Primary Outcomes (1)

• 3-year rate of any axillary recurrence

  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

Study Arms (2)

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.

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.

Interventions

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. OTHER

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.

Axillary lymph node dissection (ALND) cohort; No Axillary lymph node dissection (ALND) cohort

Eligibility Criteria

• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17), Adult (18-64), Older Adult (65+)
• 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.

You may qualify if:

• 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

You may not qualify if:

• 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)

Sponsors & Collaborators

• University Hospital, Basel, Switzerland: lead

Study Sites (1)

Department Breast, Abdomen, Pelvis; Universitätsspital Basel

Basel, 4031, Switzerland

Location

MeSH Terms

Conditions

Breast Neoplasms; Triple Negative Breast Neoplasms

Condition Hierarchy (Ancestors)

Neoplasms by Site; Neoplasms; Breast Diseases; Skin Diseases; Skin and Connective Tissue Diseases

Study Officials

• Walter P. Weber, Prof. Dr. med.

  Department Breast, Abdomen, Pelvis

  PRINCIPAL INVESTIGATOR

• Giacomo Montagna, MD MPH

  Breast Service, Department of Surgery; Memorial Sloan Kettering Cancer Center

  STUDY DIRECTOR

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: RETROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: April 16, 2026
• First Posted: April 23, 2026
• Study Start: February 1, 2026
• Primary Completion (Estimated): December 1, 2027
• Study Completion (Estimated): December 1, 2027
• Last Updated: April 23, 2026

Record last verified: 2026-04

Locations

CH (1)