Response in breast vs axilla after neoadjuvant treatment and implications for nonoperative management of invasive breast cancer

Abstract

Improved imaging and neoadjuvant chemotherapy (NAT) have led to higher pathologic complete response rates (pCR) in patients with invasive breast cancer. This has questioned the necessity of surgery and axillary lymph node (ALN) dissection in these patients. Prospective clinical trials are implementing extensive core biopsies of the tumor bed of patients with clinical complete response as a means to identify and spare them breast surgery. In addition, it is anticipated that patients with pCR are most likely going to have no or minimal disease in ALN as well. To verify the feasibility of these trials, we performed a pathologic analysis of all our patients who have undergone NAT from 2009 to present. Using pathology data base, we identified 362 patients treated with neoadjuvant chemotherapy followed by surgery. Clinical and pathologic information including gross and microscopic descriptions as well as biomarker status was collected. pCR was 50% for patients with negative ALN pretreatment but only 28% for patients with positive ALN at diagnosis. Despite achieving pCR in the breast, up to 10% of patients with positive ALN and 1% with negative ALN had persistent disease. Eight percent of patients that were presumed to have no ALN disease either clinically and or by imaging were found to have metastatic carcinoma in ALN. The metastases were predominantly (80%) <5 mm, and not palpable on physical examination and or due to biopsy sampling error. pCR in breast and ALN directly correlated with tumor size, ALN disease, and Her2 positive and triple negative receptor phenotype. In breast cancer patients who are node positive at time of diagnosis with pCR in the breast after neoadjuvant chemotherapy, residual lymph node disease was very uncommon. Further study is warranted to select patients who may avoid breast and axillary surgery post neoadjuvant chemotherapy.

Axillary response and outcome in breast cancer patients after neoadjuvant treatment: The role of radiotherapy in reducing recurrence in ypN0 patients with initially cN+ stage

“…We also observed that the axillary pCR rate varied with the breast MP grade. However, axillary pCR is only a moderate predictor of breast pCR (3,5,12). Therefore, the extent of axillary response and ypN stage may play different roles in predicting prognosis and guiding treatment.…”

“…Further analysis indicates that Ki67 10-20%+ patients may be the most axillary responsive group. Hank Schmidt et al (3). and Diego Flores-Funes et al ( 14).…”

“…Axillary pCR is a potential prognostic indicator of better 5-year overall survival (OS) (2). Breast pCR is highly consistent with axillary pCR, especially in HER2+ and triple negative breast cancer (TNBC) (3,4). The HER2+ breast cancer and TNBC were also reported to have the highest axillary pCR rate (5).…”

Post-Neoadjuvant Treatment Strategies for Patients with Early Breast Cancer

“…The pathological evaluation of post-NAC samples remains the gold standard for assessing tumor response to neoadjuvant treatments. It is extremely important to determine the degree of pathological response, which may differ between the primary tumor and the axillary lymph node metastases, and to evaluate the histological and biological characteristics of the residual tumor in both the breast and the axilla [ 56 , 57 ]. Pathologists have adopted a different approach for the macroscopic assessment, extent of sampling, and microscopic analyses of post-NAC surgical samples.…”

Pathology after neoadjuvant treatment – How to assess residual disease

“…After NAT, approximately 40% of patients with breast cancer achieve a pathological complete response (pCR), best defined as the absence of invasive carcinoma cells both in the breast and in the examined ALN [ 11 ]. It should be noted that the degree of response may vary between the primary tumor and the ALN metastases, and among the metastases themselves [ 12 , 13 ].…”