Impact of targeted axillary dissection on axillary lymph node dissection rates compared with sentinel lymph node biopsy in cN1 breast cancer patients after neoadjuvant chemotherapy: A single-centre study.

e12675 Background: In clinically node positive (cN1) breast cancer patients post neoadjuvant chemotherapy (NACT), Axillary de-escalation strategies aim to minimise morbidity without compromising oncological safety. Sentinel lymph node biopsy (SLNB) and targeted axillary dissection (TAD) are commonly employed techniques; however, comparative data evaluating technical failure and the need for axillary lymph node dissection (ALND) remain limited. We compared SLNB and TAD in terms of technical performance and rates of ALND in patients post NACT. Methods: This was a prospective two-centre study including biopsy proven node positive breast cancer (cN1) patients post NACT from January 2023 - November 2025 post NACT who were then converted to ycN0 were included. axillary surgical management differed by participating centre: where one centre patients underwent SLNB , while those treated at another centre underwent TAD. The primary endpoint was the rate of completion ALND in view of technique failure. Technique failure was defined as failed mapping, retrieval of < 3 nodes, failure to retrieve the clipped node. Secondary end points included residual nodal positivity and QOL between the two cohorts. Categorical variables were compared using chi-square or Fisher's exact tests, with statistical significance defined as p < 0.05. Results: Baseline clinicopathological characteristics were comparable between the two groups. A total of 108 patients were included, with 54 in each group. Failed mapping was was uncommon in both cohorts (0% SLNB vs 1.9% TA; p = 0.50). Retrieval of < 3 nodes occurred significantly more in the SLNB group compared with the TAD group (37% vs 11.1%; p = 0.0029). Failure to retrieve clipped node was rare and similar between groups (0% vs 1.9%; p = 0.50). The overall rate of required ALND was significantly higher in the SLNB cohort compared with the TAD cohort (37.0% vs 14.8%; p = 0.0087). Conclusions: In cN1 breast cancer patients after NACT, TAD was significantly associated with lower rates of required ALND due to technical failure compared with SLNB, primarily due to improved nodal retrieval. These findings support TAD as a more reliable strategy that may reduce surgical over treatment without compromising technical adequacy, thus also improving quality of life with lower rates of lymphoedema and shoulder morbidity. Technical failure rates of SLNB vs TAD. SLNB (N=54) TAD (N=54) FAILED MAPPING YES 0 1 (1.85%) <3 NODES 20 (37.04%) 6 (11.11%) CN NOT RETRIEVED YES 0 1 (1.85%) TOTAL RATE OF ALND REQUIRED 20 (37.04%) 8 (14.81%)