Axillary pCR and Imaging Accuracy Post-NACT in Node-Positive Breast Cancer

Overview

This retrospective study of 142 node-positive breast cancer patients evaluated factors influencing axillary pathological complete response (pCR) after neoadjuvant chemotherapy (NACT) and assessed imaging modalities for detecting residual axillary disease. HER2 positivity and progesterone receptor negativity correlated with higher axillary pCR rates, while PET-CT and ultrasonography demonstrated high specificity but moderate sensitivity in identifying residual metastasis.

Background

Axillary lymph node status is critical for prognosis and treatment planning in breast cancer. Sentinel lymph node biopsy (SLNB) has become the standard for axillary staging in clinically node-negative patients, while neoadjuvant chemotherapy (NACT) is increasingly used to downstage tumors and axillary disease, especially in triple-negative and HER2-positive subtypes. Imaging modalities such as ultrasonography (USG), mammography (MG), MRI, and PET-CT are employed to evaluate axillary response after NACT, but their accuracy varies. Optimizing axillary management post-NACT remains controversial, with ongoing debate regarding the role of SLNB, axillary dissection, and targeted axillary dissection.

Data Highlights

Key Findings

• Axillary pathological complete response (pCR) was achieved in 54.9% of patients after NACT.
• HER2-positive and progesterone receptor (PR)-negative tumors were significantly associated with higher rates of axillary pCR (p < 0.05).
• Luminal A and B breast cancer subtypes showed lower axillary response rates compared to HER2-rich and triple-negative subtypes.
• PET-CT demonstrated a specificity of 91.2% and a negative predictive value (NPV) of 74.02% for detecting residual axillary metastasis post-NACT.
• Ultrasonography (USG) showed a specificity of 84.6% and an NPV of 76.52% in the same setting.
• Imaging modalities have modest sensitivity and should complement, not replace, pathological axillary staging after NACT.

Clinical Implications

Patients with PR-positive and HER2-negative tumors have a lower likelihood of axillary pCR and require careful post-NACT evaluation. PET-CT and USG can guide assessment of axillary lymph nodes after NACT due to their high specificity, but their limited sensitivity necessitates confirmation by pathological staging. These findings support the selective use of imaging to inform surgical decision-making and highlight the need for further prospective trials to identify patients who may safely avoid axillary dissection.

Conclusion

Axillary pCR rates vary by molecular subtype, with HER2-positive and triple-negative tumors responding better to NACT. Imaging modalities such as PET-CT and USG provide valuable but complementary information for axillary assessment post-NACT, underscoring the importance of integrating imaging with pathological evaluation to optimize axillary management.

References

1. Evaluation of Axillary Pathological Complete Response and Imaging Diagnostic Performance Following Neoadjuvant Chemotherapy in Breast Cancer: A Retrospective Single-Center Analysis