Predictive factors of axillary pathological complete response in HER2-positive breast cancer patients treated with...

Axillary lymph node dissection (ALND) is associated with significant morbidity in breast cancer patients. In HER2-positive (HER2+) breast cancer, neoadjuvant chemotherapy (NAC) combined with anti-HER2 therapy can achieve high rates of pathological complete response (pCR), supporting the de-escalation of axillary surgery. Identifying reliable predictors of axillary pCR is essential for safely omitting ALND in selected patients.

This retrospective cohort study included 60 women with HER2+ breast cancer and axillary involvement treated with NAC followed by surgery between 2015 and 2022. All patients had pre- and post-treatment mammography, ultrasound, and MRI. The variables analyzed included age, Ki-67 index, hormone receptor status, breast and axillary radiological and pathological response (rCR, pCR), number of suspicious lymph nodes, and type of axillary surgery. Univariate and multivariate logistic regression models were performed to identify independent predictors of axillary pCR.

Axillary pCR was achieved in 85% of patients. On univariate analysis, axillary rCR (OR = 5.83; 95% CI: 1.30-26.12; p = 0.021) and breast rCR (OR = 6.79; 95% CI: 1.27-36.34; p = 0.025) were significantly associated with axillary pCR. Multivariate analysis identified axillary rCR (OR = 17.98; 95% CI: 1.43-225.93; p = 0.025) and Ki-67 index (OR = 0.90; 95% CI: 0.82-0.99; p = 0.045) as independent predictors of axillary pCR.

Axillary rCR and Ki-67 are independent predictors of axillary pCR in HER2+ breast cancer patients treated with NAC. These findings may help optimize axillary management and support less invasive approaches. Further multicenter studies should validate predictive models and refine imaging criteria for axillary response assessment.

QuestionIdentifying predictive factors for axillary pCR in HER2+ breast cancer patients undergoing NAC. FindingsAxillary radiological complete response predicted axillary pCR in univariate (p = 0.021) and multivariate analyses (p = 0.025), while Ki-67 was marginally significant in the multivariate model (p = 0.045). Clinical relevanceRecognizing reliable predictors of axillary pCR may support the omission of ALND in selected HER2+ patients, minimizing surgical morbidity.