Risk-adapted Postmastectomy Radiotherapy Based On Locoregional Recurrence For PT1-2N1M0 Breast Cancer

Part ?:Risk Stratification for Patients with Early Stage Breast Cancer(pTl-2N1M0)Receiving PostmastectomyObjective:The definite role of postmastectomy radiotherapy(PMRT)following chemotherapy(CT)for early stage intermediate-risk(pTl-2N1M0)breast cancer is not well-defined.The aim of this study was to establish risk-adapted model on the basis of locoregional recurrence and evaluate the role of PMRT for pTl-2N1M0 breast cancer.Material and methods:A total of 2413 patients with pTl-2N1M0 breast cancer were retrospectively reviewed.Of them,588 patients received PMRT,and 1825 patients did not.A comprehensive comparative study was performed using multivariable and risk-adapted model.Results:In patients without PMRT,multivariable analysis indicated that age(?45 years vs>45 years),tumor site(inner+central region vs lateral region),molecular subtype(HER2 enriched + Triple negative vs Luminal A + Luminal B),pathologic T stage(T2 vs T1)and positive lymph node numbers(2+3 vs 1)were independent factors for LRRFS.Patients with T1-2N1 breast cancer were classified as low-risk(0-1 risk factor,43.5%),intermediate-risk(2 risk factors,34.1%)and high-risk groups(?3 risk factors,22.5%)based on these independent factors.There was significantly difference in LRRFS and survivals between three risk groups.Low-risk patients had significantly better outcome than intermediate-risk and high-risk patients,with 5-year OS,DFS and LRRFS rates of 96.6%,92.5%and 97.3%for the low-risk group,95.9%,87.9%and 94.4%for the intermediate-risk group and 87.1%(P<0.001),74.4%(P<0.001)and 84.3%(P<0.001)for the high-risk group.Conclusion:T1-2N1 breast cancer has variable locoregional recurrence rates.The use of a risk-adapted model to select PMRT is a viable effective strategy.Part ?:Risk-adapted Postmastectomy Radiotherapy for Early Stage Breast Cancer(pTl-2NlM0)Objective:The definite role of PMRT following chemotherapy for intermediate-risk(pT1-2N1M0)breast cancer is not well-defined.The aim of this study was to establish a risk-adapted radiotherapy strategy for intermediate-risk breast cancer.Material and methods:A total of 2413 patients with pT1-2N1M0 breast cancer were retrospectively reviewed.Of them,588 patients received PMRT,and 1825 patients did not.A comprehensive comparative study was performed using risk-adapted model and propensity score-matched(PSM)analyses.Results:Multivariable analysis indicated that age ?45,tumor site in inner and central region,HER2 enriched or Triple negative,pathologic T2 and 2-3 positive lymph node were independent adverse factors for LRRFS.Patients with T1-2N1 breast cancer were classified as low-risk(0-1 risk factor),intermediate-risk(2 risk factors)or high-risk groups(?3 risk factors)based on these independent factors.In low-and intermediate-risk groups,there was no difference in LRRFS,DFS and OS(P>0.05)between patients who received PMRT and those did not receive PMRT.In high-risk group,compared with no PMRT,PMRT resulted in similar DFS(79.8%vs 74.4%,P = 0.127)and OS(86.8%vs.87.1%,P = 0.174),but signficantly higher LRRFS(93.3%vs 84.3%,P = 0.002).After PSM adjustment,no significant difference in LRRFS,DFS and OS was observed between PMRT and no PMRT groups in low-risk group.In intermediate-risk group,compared with no PMRT,PMRT resulted in improved LRRFS(95.2%vs 91.0%,P =0.037),but no significant difference in DFS and OS.However,in the high-risk group,PMRT resulted significantly better LRRFS and DFS than no PMRT,and had a tendency to improve OS.The 5-year LRRFS,DFS and OS rates were 93.3%,79.7%and 86.6%for PMRT,compared with 78.5%(P<0.001),69.5%(P = 0.038)and 85.7%(P = 0.080)for no PMRT.Conclusion:Risk-adapted PMRT for intermediate and high-risk patients is a viable effective strategy for T1-ZN1 breast cancer.Better survivals can be achieved in these patients especially in high-risk group.More samples on this subject is justified.