Association of Axillary Lymph Node
Dissection With Oncological
Outcomes in Patients With Residual
Micrometastases After Neoadjuvant
Chemotherapy: The OPBC07/microNAC study
SynopsisPrincipal investigators
Giacomo Montagna, MD MPH
Breast Service, Department of Surgery
Memorial Sloan Kettering Cancer Center300 East 66th Street
New York, NY 10065(T) +1 646 888 6891
(F) +1 646 888 4921
(E) montagng@mskcc.org

Prof. Dr. med. Walter P. Weber
Head of Division Breast Surgery
University Hospital Basel
Spitalstrasse 21CH 4031 Basel(T) +41 61 328 61 49(E) walter.weber@usb.ch

Clinical question: Is axillary dissection indicated for residual micrometastases after neoadjuvant
chemotherapy?
Study design: Multicenter retrospective cohort study
Population: Consecutive patients with residual micrometastases after neoadjuvant chemotherapy
treated with or without axillary dissection.
Minimum number of cases per institution: 5
Eligibility:•

Women and men aged 18 years or older with a diagnosis of stage I-III breast cancer (anyhistological and receptor subtype)•

Completed neoadjuvant chemotherapy•

Residual micrometastases detected on SLNB or TAD or MARI biopsy (on frozen section orfinal pathology)•Concomitant presence of ITCs on other sentinel nodes is allowed•

Received axillary treatment with completion ALND, axillary RT, both, or none
At least 1-year follow-up (inclusion should end in May 2023)
Had surgery at any time point until May 2023 at the latest
For cN0 at presentation: any axillary staging technique including palpation is allowed (dualtracer mapping not required for SLNB)For cN+ at presentation: cytological or histological confirmation is required. Axillary
staging should be performed with sentinel lymph node (SLNB) with dual mapping ortargeted axillary dissection (TAD: imaging-guided localization of sampled node incombination with SLN procedure with or without dual mapping) or the MARI (MarkingAxillary Lymph Nodes with Iodine Seeds) procedure
Prior history of stage I-III (not stage IV) BC is allowed

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Exclusion:• Did not undergo SLNB/TAD/MARI (i.e. went straight to ALND)• Presence of ITCs alone or macrometastases on the sentinel node (or TAD node or MARInode)• Stage IV disease at presentation• Inflammatory breast cancer at presentation• Neoadjuvant endocrine therapy• Micrometastases detected by OSNA
Primary outcomes:• 5-year rate of any axillary recurrence (defined as isolated or combined with local or distantrecurrence) and 5-year rate of isolated axillary recurrence• To compare 5-year rate of axillary recurrence in patients treated with and without axillary
dissection

The OPBC-07/microNAC study, Study Synopsis V2.0, January 2024

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Secondary outcomes:• Proportion with patients with additional positive lymph nodes (micro- or macrometastases)
at ALND• 5-year rates of locoregional and any invasive recurrence• To compare 5-year rate of locoregional and any invasive recurrence in patients treated withand without axillary dissection
List of variables to be collected:• Center• Age (at surgery)• Race (Asian, Black, Caucasian, other)• Ethnicity (Hispanic, non-hispanic)• cT at presentation• cN0 or cN+ (biopsy-proven) at presentation• Date of surgery• Type of breast surgery: BCT/mastectomy• Type of axillary surgery-SLNB with dual mapping (in cN+ and cN- cases) or-TAD (in cN+ cases)- single or dual mapping?
- MARI-SLNB with single tracer (in cN0 cases)• Number of SLNs removed• Number of SLNs with micromets• Number of concomitant SLNs, TAD, or MARI nodes with ITCs
• Detection on frozen section? y/n• Method of detection? H&E or IHC?
• ALND y/n• Number of additional LNs removed• Number of additional positive lymph nodes• Size of the largest nodal metastasis found in the ALND specimen:
ITCs/micrometastasis/macrometastasis• Histology (NST/lobular/other)• Breast pCR: yes/no• Residual tumor size in the breast: size (cm)• Tumor grade• Receptor status- ER+ and/or PR+ HER2-;- ER+ and/or PR+/Her2+;- ER-/PR- Her2+;- ER-/PR-/HER2-;• Type of NAC regimen for HER2- (AC-T/AC-t + Carbo/AC-free regimen/other)• Type of NAC regimen for HER2+ (AC-TH/AC-THP/TCHP/other)

The OPBC-07/microNAC study, Study Synopsis V2.0, January 2024

page 3 of 4•••••Adjuvant capecitabine: yes/noIf HER2+: type of post-surgical anti-HER2 treatment (H/HP/TDM-1)
If HR+: received adjuvant endocrine therapy: yes/no- if yes: type of endocrine therapy
Adjuvant Abemaciclib yes/noAdjuvant Olaprabib yes/noRadiotherapy: yes/no• Target Volume:
Whole breast irradiation: y/no
Chest wall irradiation: y/no
Regional nodal irradiation y/no
Follow-up
Date of last follow up• Recurrence: yes/no• Type of recurrence: local/regional/locoregional/synchronous (regional and distant, local anddistant, locoregional and distant)• Type of regional recurrence: axillary only, axillary and supraclavicular or internalmammary, supraclavicular or internal mammary without axillary• Date of recurrence• Deceased: yes/no• Date of death• Cause of death

The OPBC-07/microNAC study, Study Synopsis V2.0, January 2024

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