AB011. SOH22ABS170. Incidence of treatment effect in patients with an axillary pathologic complete response after neoadjuvant chemotherapy for breast cancer
Clinical Breast Session

AB011. SOH22ABS170. Incidence of treatment effect in patients with an axillary pathologic complete response after neoadjuvant chemotherapy for breast cancer

Katie Doogan1, Alex Zaborowski1, Lauren O’Connell1, Sorcha McNally2, Janice Walshe3, Cecily Quinn4, Denis Evoy1, James Geraghty1, Damian McCartan1, Ruth Prichard1

1Department of Breast Surgery, St. Vincent’s University Hospital, Dublin, Ireland; 2Department of Radiology, St. Vincent’s University Hospital, Dublin, Ireland; 3Department of Medical Oncology, St. Vincent’s University Hospital, Dublin, Ireland; 4Department of Pathology, St. Vincent’s University Hospital, Dublin, Ireland

Background: De-escalation of axillary surgery following neoadjuvant chemotherapy (NACT) for patients with node positive disease at diagnosis have focused on ensuring a low false negative rate for those who undergo sentinel lymph node biopsy (SLNB) only. Histopathological evidence of treatment effect is one surrogate that supports an axillary pathological complete response (pCR). This study aimed to assess rates of histological treatment effect in patients who have an axillary pCR following axillary surgery post NACT.

Methods: A consecutive series of patients with cytologically proven node-positive breast cancer who received NACT and achieved a nodal pCR on SLNB or axillary lymph node dissection (ALND) between 2016–2021 were retrospectively analysed. The primary outcome of interest was identification of histological treatment effect in axillary nodes.

Results: A total of 257 patients (median age 48 years) received NACT of which 180 had cytologically-proven node-positive disease. The median nodal yield at SLN was 4 (range, 1–9). Eighty-three patients (46%) attained an axillary pCR. Histological evidence of treatment effect on was identified in 62% of patients overall, but was more common in those undergoing ALND (87%) than in the SLN group (56%, P=0.04). Neither tumour subtype, grade nor breast pCR were associated with treatment effect on univariate analysis.

Conclusions: Histological evidence of treatment effect was only identified in 56% of patients deemed ypN0 on the basis of a post-neoadjuvant SLN and cannot be utilised as a stand-alone surrogate for confirmation of a true negative SLN. Strategies such as nodal marking/targeted axillary dissection may offer a more robust method of axillary staging post NACT.

Keywords: Axillary pathologic complete response; axillary lymph node dissection (ALND); breast cancer; neoadjuvant chemotherapy (NACT); sentinel lymph node biopsy (SLNB)

Acknowledgments

Funding: None.

Footnote

Conflicts of Interest: The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

doi: 10.21037/map-22-ab011
Cite this abstract as: Doogan K, Zaborowski A, O’Connell L, McNally S, Walshe J, Quinn C, Evoy D, Geraghty J, McCartan D, Prichard R. AB011. SOH22ABS170. Incidence of treatment effect in patients with an axillary pathologic complete response after neoadjuvant chemotherapy for breast cancer. Mesentery Peritoneum 2022;6:AB011.

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