Effect Of Postmastectomy Radiotherapy On Triple-negative Breast Cancer With T1-2 And 1-3 Positive Axillary Lymph Nodes

Background:There is consensus on the routine use of PMRT in patients with four or more positive axillary lymph nodes,but the benefits of post-mastectomy radiotherapy(PMRT)in women with T1-2 and N1 still remain controversial,and most previous reports have not investigated triple-negative breast cancer(TNBC).The aim of the present study is to investigate the possible benefits of post-mastectomy radiotherapy on survival of TNBC with T1-2 and 1-3 positive axillary lymph nodes?Methods:Data from the Surveillance,Epidemiology,and End Results Program(SEER)of the United States between 2010 and 2012 were used to obtain 855 TNBC patients T1-2 and 1-3 Lymph Nodes involved available.These patients were divided into two arms(RT and no RT)according to the radiationtherapy status.A Chi-squared test was used to compare the demographic and clinical characteristics of the included cases between the two groups categorized by radiationtherapy status.The Kaplan-Meier analysis was performed to generate survival curves,and the log-rank test was used to compare the unadjusted BCSS and OS rates of patients with different lymph node status.Univariate Cox proportional hazard mode analysis were performed using to estimate hazard ratio(HR).Results:A total of 855 patients met the eligibility criteria for our study,and average age was 53 years old.The median follow-up time was 27 months,and there were 110 death events occurred,94 of whom died of breast cancer.Patients in the triple-negative group were more likely to have invasive ductal carcinoma and grade III tumors,accounting for 88.9% and 87.0%,respectively ? Kaplan-Meier plot showed that post-mastectomy radiotherapy didn't decrease the risk of mortality in the women with T1-2 and 1-3 involved lymph nodes.And no significantly difference in OS and BCSS were observed between the groups with PMRT and without PMRT,regardless of involved numbers of LN and age(all P>0.05).In multivariate analysis,marital status was the borderline significant factor for overall survival(P= 0.052).Conclusion: PMRT was not found to improve the overall survival in TNBC patients with T1-2 N1.,but the findings needed to be further confirmed by prospective studies.