Treatment Response Correlation Between Primary Tumor And Axillary Lymph Nodes After Neoadjuvant Therapy In Breast Cancer

Background: Neoadjuvant therapy,also known as pre-surgery therapy,has been applied to a wide range of malignancies including breast cancer which has been acknowledged with an extremely high incidence in women.The neoadjuvant therapy of breast cancer is comprised of neoadjuvant chemotherapy,neoadjuvant targeted therapy(also called neoadjuvant anti-HER2 therapy)and neoadjuvant endocrine therapy.The bedrock of this strategy is neoadjuvant chemotherapy,which primarily focused on locally advanced patients(with a large tumor size or pathologically confirmed regional lymph node metastases)in the past.However,with the remarkable development of treatment concepts and drugs,the indications for neoadjuvant chemotherapy have been enlarged to cover a cluster of patients with an early clinical stage,the aim of which is to increase the success rate of breast conserving surgery(BCS)and ultimately improve the quality of life(QOL)for these women.A retrospective study on breast cancer showed that the invasive tumor content was more likely to be eradicated from the primary tumor if there was no measurable disease in the axillary lymph nodes after standardized neoadjuvant chemotherapy.On the basis of this finding,some researchers hypothesized that an excellent response of the primary tumor such as pathologic complete response(p CR)after neoadjuvant therapy,or no residual invasive tumor,may indicate a better axillary status(no or few metastases in the axillary lymph nodes)in patients with breast cancer.However,this treatment response correlation has not been investigated in Chinese breast cancer patients.Methods: Patients diagnosed with breast cancer from 2012 to 2019 and treated with neoadjuvant therapy were included in this retrospective study,conducted at the Breast Cancer Center of Chongqing(Department of Endocrine and Breast Surgery,The First Affiliated Hospital of Chongqing Medical University).Based on the Miller & Payne(MP)classification system,the treatment responses after neoadjuvant therapy were assessed and the definitions of study outcomes were determined: a pathologic complete response of the breast primary tumor(breast p CR)was defined as no evidence of residual invasive carcinoma in the excisional breast specimen(yp T0/is),while a p CR of the axillary lymph nodes(axilla p CR)was defined as the absence of measurable or metastatic disease in the excisional specimens of axillary lymph nodes(yp N0).Enrolled patients were divided into the p CR group(breast p CR / axilla p CR)and the non-p CR group(breast non-p CR / axilla non-p CR)when separately analyzing the treatment response of breast and axillary lymph nodes.We used univariate analysis to identify clinicopathological factors with significant differences or clinical relevance between the two groups(p CR vs non-p CR)of breast pathologic response and axilla response,respectively.These factors were further included in the multivariate logistic regression model to determine the characteristics affecting the pathologic response after neoadjuvant therapy.Furthermore,association rules analyses were utilized to investigate the correlation between the pathologic response of the primary tumor and that of the axillary lymph nodes on the basis of the clinicopathological parameters at baseline.Results: Multivariate analysis showed that breast pathologic response was influenced by tumor size,regional lymph node involvement,histological grade,progesterone receptor status,and Ki-67 expression.The potential influencing factor for the pathologic response of the axilla was found to be regional lymph node classification.The findings from association rules analyses demonstrated that when a p CR in the breast was achieved among patients with c T2N0 and hormone receptor-negative disease,the axilla response in these patients was also highly likely to be p CR(the likelihood for axilla p CR was more than 90%).However,c T3N1-2 patients hardly achieved p CR for both the primary tumor and axillary lymph nodes(mean confidence,0.9 637).The clinicopathological factors accounting for the inconsistent response between the breast and the axilla were found to be hormone receptor-positive,human epidermal growth factor receptor 2(HER2)-negative,and low Ki-67 expression.Conclusions: Our findings suggest a strong correlation between breast p CR and axilla p CR among patients with specific characteristics.These findings provide a basis for the selection of candidates for clinical trials on the omission of axillary surgery and can promote the advancement of precision medicine in breast cancer.