Impact Of Pathological Response Of Primary Tumor On Survival Of YpN0 Stage Breast Cancer

Objective:To investigate the impact of pathological response of primary tumor on survival of breast cancer with different ypN stages,and the prognostic value of which in different breast cancer subtypes.Patients and methods:We reviewed the medical records of 935 female patients with positive lymph nodes of StageⅡ-Ⅲinvasive ductal carcinoma of breast,who received neoadjuvant chemotherapy and modified radical mastectomy from January2003 to December 2013 at Tianjin Medical University Cancer Institute and Hospital.According to the pathological response of primary tumor,we classified different ypN stages into non-invasive carcinoma group（ypT0/is）and invasive carcinoma（ypT≥1mic）group respectively,which was named adjusted-ypN stages.We analyzed the effect of adjusted-ypN stages on the survival of patients with breast cancer by Kaplan-Meier survival analysis,and we explored the correlation between adjusted-ypN stages and prognosis of breast cancer by univariate and multivariate analysis.Then we carried out a stratified analysis to estimate the prognostic effect of adjusted-ypN stages on the survival of patients with various breast cancer subtypes.The guiding significance of adjusted-ypN stages in the clinical treatment of breast cancer was discussed in the end.We used Kaplan-Meier survival analysis to determine DFS and OS.Log-rank test was used to compare differences among subgroups.Multivariate Cox regression was used to test the independency of various factors.Chi-square test was used to analyze clinical and pathological features.P values<0.05 were considered as statistically significant.Results:935 female breast cancer patients,meeting the condition,who received neoadjuvant chemotherapy were included in this study.We used Kaplan-Meier survival analysis to establish survival curves and observed that the prognosis of patients who received pathologic complete response of primary tumor after neoadjuvant chemotherapy was significantly better than that of patients with residual invasive cancer in primary tumor(P_DFS<0.001,P_OS<0.001).With the increase of ypN stages,the risk of recurrence or metastasis and the proportion of tumor-related deaths in breast cancer patients increased gradually(P_DFS<0.001,P_OS<0.001).Considering that different ypN stages may contain two types of primary tumors with various prognosis,the prognostic value of the ypN staging system is reduced.So we combined ypN stages with pathologic remission of primary breast cancer to form adjusted-ypN stages.5-year disease-free survival rates and 5-year overall survival rates of ypN0（ypT0/is）,ypN0（ypT≥1mic）,ypN1,ypN2 and ypN3 were decreased gradually,and the curves of DFS（P<0.001）and OS（P<0.001）were significantly different in various adjusted-ypN stages.Multivariate Cox regression showed that the adjusted-ypN stages were the independent factor predicting DFS and OS(P_DFS<0.001,P_OS<0.001).Considering breast cancer subtypes,we observed that the DFS（P=0.280）and OS（P=0.378）of Luminal A breast cancer with ypN0 stage were no statistical difference respectively between ypN0（ypT0/is）group and ypN0（ypT≥1mic）group by stratified analysis,regardless of whether the primary tumor was pathologically relieved or not.And breast cancer with ypN3 stage still had the worst prognosis among different molecular types of breast cancer.And pathologic complete response of primary tumor was closely related to the improvement of DFS and OS of Luminal B（HER-2 positive）breast cancer,Triple negative breast cancer and HER-2overexpressed breast cancer.Conclusions:The pathological response of primary tumor after neoadjuvant chemotherapy was closely related with the prognosis of breast cancer patients with ypN0 stage,which was different in distinct molecular subtypes and provided a basis for individualized treatment.