Analysis Of Prognostic Risk Factors Of T_1-2N₁M₀ Breast Cancer And Observation Of The Curative Effect Of Radiotherapy After Modified Radical Mastectomy

Objective:Whether patients with T_1-2N₁M₀stage breast cancer should receive local radiotherapy after modified radical mastectomy is still controversial.The application of post-mastectomy radiotherapy（PMRT）in patients with 1-3 positive lymph nodes is lack of evidence.This study aims to compare the prognosis of patients receiving PMRT and not receiving PMRT,observe the effects of postoperative radiotherapy,analyze the risk factors that affect the prognosis of patients,and screen high-risk populations.It is the clinical application of PMRT in T_1-2N₁M₀patients for reference.Methods:A retrospective analysis of 633 postoperative pathologically diagnosed patients with p T_1-2N₁M₀stage,the patients are divided into non-radiotherapy group and radiotherapy group according to whether they received PMRT.After admission,patients in the non-radiotherapy group were first treated with modified radical mastectomy for breast cancer.After the operation,adjuvant treatment options（including adjuvant chemotherapy,endocrine therapy,and targeted therapy）were selected based on pathological characteristics,assessment of the patient’s own condition,and responsiveness to chemotherapy drugs.Patients in the radiotherapy group received modified radical mastectomy for breast cancer.After the operation,they selected adjuvant treatment options（including adjuvant chemotherapy,endocrine therapy,and targeted therapy）based on pathological characteristics,assessment of the patient’s own condition,and responsiveness to chemotherapy drugs.After adjuvant chemotherapy,he received radiotherapy on the affected side of the chest wall and the ipsilateral regional lymph nodes.The Kaplan-Meier method is used to analyze the 3-year local recurrence-free survival（LRFS）,distant metastasis-free survival（DMFS）,disease-free survival（DFS）and overall survival（OS）of the two groups of patients,and compare radiotherapy and non-radiotherapy.The curative effect of radiotherapy,and the Cox risk model is used to analyze the risk factors related to tumor recurrence.Results:1.After 3 years of follow-up,22 patients（3.5%）had local recurrence,54 patients（8.5%）had distant metastasis,and 16 patients died during the follow-up period.The3-year LRFS of all patients is 96.5%,DMFS is 91.5%,DFS is 90.2%,and OS is 97.5%.2.There are 269 patients in the non-radiotherapy group and 364 patients in the radiotherapy group.The 3-year local recurrence-free survival rates of the non-radiotherapy group and the radiotherapy group are 94.8%and 97.8%（P=0.038）,and the distant metastasis-free survival rates are 89.6%and 92.9%（P=0.146）,and the DFS are 87.4%and 92.3%（P=0.037）,the OS are 97.8%and 97.3%（P=0.687）.The results show that there is a statistical difference between the non-radiotherapy group and the radiotherapy group on the 3-year LRR and DFS,but the difference on DM and OS are not statistically significant.3.Multivariate analysis shows that histology grade III,tumor located in the inner quadrant and central area,postoperative non-radiotherapy and HER-2 type are independent risk factors for local regional recurrence;histology grade III,tumor located inner quadrant and central area,pathological type of other types of cancer,T₂stage,no postoperative radiotherapy,and molecular type of HER-2 are independent risk factors for disease-free survival.Conclusion:1.Radiotherapy for patients with T_1-2N₁M₀breast cancer after modified radical mastectomy can reduce the 3-year local recurrence rate and improve the disease-free survival rate,but has no significant effect on the distant metastasis rate and the 3-year overall survival rate.2.Non-radiotherapy after modified radical mastectomy is an independent risk factor affecting the 3-year local recurrence and disease-free survival of patients with T_1-2N₁M₀breast cancer.