De-escalation of axillary surgery post neoadjuvant therapy in hormone-positive breast cancer: Feasible or futile

Abstract

A proportion of patients with breast cancer presenting with nodal metastases will undergo an axillary pathological complete response (pCR) following neoadjuvant chemotherapy (NACT). The probability of an axillary pCR is highly dependent on tumour subtype with the lowest probability in patients with estrogen receptor (ER) positive disease. A retrospective review was conducted of patients with symptomatic breast cancer who received neoadjuvant chemotherapy from 2013 to 2021. Inclusion criteria comprised newly diagnosed ER positive breast cancer patients with histologically proven axillary metastasis, undergoing treatment with curative intent. Univariate and multivariate analysis was performed to identify predictors of axillary pCR. Statistical analyses were performed with SPSS v.26.0. During the study period, 154 patients with biopsy confirmed axillary nodal disease and ER positive breast cancer were treated with neoadjuvant chemotherapy. Of these 35% (n=54) were also HER2 positive. Axillary pCR was significantly more likely in the patients with ER positive and HER2 positive breast cancer (pCR in 59%). In patients with HER2 negative disease only 19% attained an axillary pCR (p<0.001). On multivariate analysis of the HER2 negative cohort the only factor significantly associated with axillary pCR was a complete radiological response of the primary tumour (p=0.004). In patients without a radiological complete response, the axillary pCR rate was 16%. In patients with ER positive, HER2 negative breast cancer, the rate of axillary pCR remains low and in those without a radiological complete response in the breast primary, axillary lymph node dissection should still be considered the standard of care.