Upper outer boundaries of the axillary dissection. Result of the SENTIBRAS protocol: Multicentric protocol using axillary reverse mapping in breast cancer patients requiring axillary dissection.

Background: Two thirds of node-positive breast cancer patients have limited pN1 disease and could benefit from a less extensive axillary lymph node dissection (ALND).

Methods: 172 breast cancers patients requiring an ALND were prospectively enrolled in the Sentibras Protocol of Axillary Reverse Mapping (ARM). Radioisotope was injected in the ipsilateral hand the day before surgery. ALND was standard. Removed lymph nodes were classified into non radioactive nodes and radioactive nodes (ARM nodes). Among ARM nodes, nodes located in the upper outer part of the axilla, above the second intercostal brachial nerve and lateral to the lateral thoracic vein were identified as "zone D ARM nodes". The main objective was: feasibility of identification of the zone D ARM nodes. Secondary objectives were: metastatic involvement and lymphedema rate.

Results: 100% of patients had ARM nodes identified. The "zone D ARM nodes" were identified in 92% of cases. The rate of metastatic nodes was 60% in the all cohort, 31% in ARM nodes and 9% in zone D ARM nodes. Among those, metastatic rate was 6% in patients undergoing ALND for a positive sentinel node biopsy, 6% in case of primary ALND versus 14% after neo-adjuvant chemotherapy (p < 0.05). After 34 months of median follow up, 27% of interviewed patients had a lymphedema.

Conclusion: The ARM technique reliably identifies the "zone D ARM nodes". These nodes can also easily be identified using knowledge of axillary anatomy. In selected patients, a selective ALND sparing the zone D ARM nodes could be performed.