Risk Factors Of Locoregional Recurrence And Potential Value Of Radiotherapy In T1-T2 Node Negative Breast Cancer Patients Treated With Mastectomy

Objective: To investigate the risk factors of locoregional recurrence and potential value of radiotherapy in T1-T2 node negative breast cancer patients treated with mastectomyMethods: From January 2001 to February 2008, a total of 353 node-negative and T1-T2 breast cancer cases treated with mastectomy without adjuvant radiotherapy in Fujian Provincial Cancer Hospital were retrospectively analyzed. Of them, 99 cases(28.0%) were ≤40 years old. There were 20 patients(5.7%)with primary tumor size ≥4.5cm and the other 333 cases(94.3%)<4.5cm. The prognostic factors included number of nodes resected, lymphovascular invasion, age, pathology, primary tumor size, T staging, memenstrual status, endocrine therapy, history of benign breast disease, primary tumor location, nipple involvement, chemotherapy, chemotherapy cycle, ER, PR, HER-2 and molecular subtypes. Kaplan-Meier method was used to calculate the survival rates, and the Log-rank test was used for the comparison of the survival curves between different groups. Multivariate analyses were performed using Cox proportional hazards model. Define scoring system according to the results of Cox model, and each prognostic factor was scored as one point.Results: The median follow-up time was 115.7 months(range,1.2-238.4 months). A total of 39 cases(11.0%) had locoregional recurrence, 62 patients(17.6%) developed distant metastasis and 49 patients(13.9%) died. Chest wall was found to be the most common site of LRR(21/39,53.8%), following by the supraclavicular nodes(19/39,48.7%). The 5-year locoregional recurrence-free survival(LRFS), disease-free survival(DFS), and overall survival(OS) for entire cohort were 89.8%(95%CI = 86.7%- 92.9%)、81.0%(95%CI = 76.9%- 85.1%)and 90.0%(95%CI = 86.9%- 93.1%), respectively. The 5-year OS of patients with and without locoregional recurrence was 61.3%(95%CI= 44.3%- 74.5%) vs. 93.5%(95%CI= 90.8%- 96.2%)(c2=93.384,p=0.000)。Univariate analysis showed that age, primary tumor size, and number of nodes resected were independent factors affecting the prognosis of LRFS. Through the multivariate analysis, age ≤40 years old(HR=1.936, 95%CI=1.023-3.644, p=0.042), primary tumor size≥4.5cm(HR=4.007, 95%CI=1.761-9.115,p=0.001) and number of nodes resected≤10(HR=2.052, 95%CI=1.013-4.157, p=0.046) were found to be the independent poor prognostic factors of locoregional recurrence. According to the scoring system, the 5-year LRFS was 94.7%(95%CI=91.6%-97.8%) without any risk factors, 85.3%( 95%CI=78.8%-91.8%) with one risk factor, and 71.4%(95%CI=51.0%-84.5%) with ≥ 2 factors,(c2=17.031,p=0.000). The paired comparison showed that group with any risk factors factors had a significantly lower LRFS than those without.Conclusion: The patients with T1-2N0M0 breast cancer had achieved favorable prognosis. While those with risk factors, including age≤40 years old, primary tumor size≥4.5cm and number of nodes resected ≤10, were at higher risk of locoregional recurrence and might benefit from adjuvant radiotherapy.