Analysis Of Factors Affecting Axillary PCR After Neoadjuvant Therapy For Breast Cancer And Feasibility Of Exempting Axillary Surgery

Objective:To analyze the factors affecting axillary pathological complete response(pCR)after neoadjuvant therapy(NAT)for breast cancer,and to provide the feasibility of exempting axillary surgery for patients with pCR of the primary tumor after NAT.Methods:The clinicopathological features of 111 patients diagnosed with breast cancer in our hospital from January 2020 to June 2022 were retrospectively collected.All patients were diagnosed with ipsilateral axillary lymph nodes metastasis of breast cancer by cytology or pathology at the initial diagnosis,and the neoadjuvant treatment cycle was completed according to standards.All patients underwent axillary lymph node dissection after NAT.Axillary pCR and axillary non-pCR were judged according to whether there was residual cancer cell after the operation.The therapeutic effect of the primary tumor was evaluated by the MP(Miller and Payne)grading system.TheX~2 test was used to compare the clinicopathological characteristics of axillary pCR and axillary non-pCR patients.Logistic regression multivariate analysis was used to analyze the risk factors of axillary pCR.The feasibility of exempting axillary surgery after NAT was explored when MP grade 5 with or MP grade 5 without ductal carcinoma in situ(DCIS).Results:111 patients with breast cancer who had completed surgical treatment were included.There were 63 patients with HER-2+breast cancer,and 40 patients with the primary tumor reached pCR,with a pCR rate of63.49%.There were 19 patients with triple-negative breast cancer,and 7patients with the primary tumor achieved pCR,with a pCR rate of 36.84%.There were 29 patients with Luminal(HER-2-)breast cancer,4 patients with the primary tumor achieved pCR,and the pCR rate was 13.79%.There were 47patients of axillary non-pCR and 64 patients of axillary pCR.Univariate analysis showed that the expression status of ER(X~2=13.144,P<0.001),the expression status of PR(X~2=16.212,P<0.001),molecular type(X~2=23.594,P<0.001),neoadjuvant therapy(X~2=17.136,P<0.001)and MP grades(X~2=45.024,P<0.001)were the factors affecting axillary pCR.Logistic regression multivariate analysis showed that MP grade 5 relative to MP grades≤3,and MP grade 5 relative to MP grade 4 increased the probability of axillary pCR(P<0.001,P=0.001).There were 51 patients of MP grade 5 after NAT,including 46 patients of axillary pCR[HER-2+(HR-):17/18,HER-2+(HR+):19/22,Triple negative:7/7,Luminal(HER-2-):3/4].When MP grade 5,the negative predictive value(95%CI)=90.2%(81.7%～98.6%),specificity(95%CI)=71.9%(60.6%～83.2%),false negative(95%CI)=10.6%(1.5%～19.8%)of residual axillary lymph nodes.When the primary tumor was MP grade 5 without DICS(yp T0),only 2 of 43 patients did not reach the axillary pCR.The negative predictive value(95%CI)of yp T0 for residual axillary lymph nodes was 95.3%(88.8%～101.9%),specificity(95%CI)=64.1%(52.0%～76.1%),false negative(95%CI)=4.3%(-1.7%～10.2%).Conclusion:Compared with MP grades≤3 and MP grade 4,and MP grade 5 of the primary tumor after NAT increased the probability of axillary pCR after NAT in breast cancer patients.When MP grade 5(pCR of the primary tumor),the high negative predictive value of residual axillary lymph nodes and lower false negative provided the feasibility of axillary surgery exemption and it is promising in the yp T0 population.However,additional large-sample prospective clinical trials and long-term survival data are needed.