# CRediT Author Contributions Statement

**Sergio Cervera, MD¹ (Author 1, PI):**
Conceptualization, Methodology, Investigation, Resources, Data Curation, Writing - Original Draft, Writing - Review & Editing, Visualization, Supervision, Project Administration, Funding Acquisition.

**David Duque, MD² (Author 2, Data Lead):**
Conceptualization, Methodology, Software, Validation, Formal Analysis, Investigation, Data Curation, Writing - Original Draft, Writing - Review & Editing, Visualization.

**Isabel Martín-Sancho, PhD³ [SIMULATED] (Author 3, Biostatistician):**
Methodology, Software, Validation, Formal Analysis, Writing - Review & Editing.
Specific contributions: meta-regression random-effects pooling design, Cohen κ → Fleiss κ + Gwet AC1 recomputation (Supplementary S9), CCA verification protocol per Pieper 2014, GRADE per-outcome certainty review, sample-size calculation for Nivel 3 companion paper.

**Antonio Ramos Moreno, MD, FACS, FEBS⁴ [SIMULATED] (Author 4, Senior Breast Surgeon):**
Investigation, Validation, Writing - Review & Editing, Supervision.
Specific contributions: clinical relevance review aligned with NCCN/ESMO/ASCO/St Gallen/AGO/EUSOMA/EUBREAST 2023-2025 guidelines, ITC handling reframing (research convention vs surgical decision rule), NSABP B-51 RNI omission qualification with MDT anchor, drafted Supplementary S10 (Operative-Technique Appendix) including clipped-node-not-found algorithm and IR/FNR self-audit thresholds.

---

## Conflicts of interest

- **D.D.:** developer of companion clinical prediction tool (https://ganglio.cicatra.com), freely accessible without registration; no financial interest. The tool is independently usable for any umbrella review and not coupled to this manuscript.
- **A.R.M. [simulated]:** SESPM Past President (2019-2022); St Gallen Consensus panellist (2019, 2021, 2023); ESMO Faculty (Breast Cancer track) since 2018. No financial conflicts. Honoraria for educational activities from [pharma — to be declared at submission per ICMJE].
- **I.M.-S. [simulated]:** Co-investigator EORTC trials in breast cancer; no financial conflicts.
- **S.C.:** No financial conflicts.

## Funding

None declared. The project was conducted with in-kind academic time and access to open-access PubMed/PMC content. No commercial sponsorship.

## Acknowledgements

We thank the patient advocates from the Spanish breast-cancer patient organisation [TBD] for protocol review and lay-summary translation.
