| Objective: For T1 triple negative breast cancer(TNBC),breast-conserving therapy(BCT)and mastectomy(ME)are two feasible surgical manners,but studying the prognostic influence of two surgical methods on these patients is less common.And the prior studies did not further explore the impact of surgical methods on prognosis in patients with different lymph node staging.So,the present study was aimed to assess the influence of BCT and ME on the overall survival(OS)for T1 TNBC patients with different metastasis status of lymph node,in order to provide sound advice for the clinic practice.Methods: By visiting the Surveillance,Epidemiology,and End Results(SEER)database of the USA online,we collected medical records of T1 TNBC patients diagnosed in 2010-2014,with non-distant metastasis.The metastasis status of lymph node was indirectly represented by tumor stage in the study population.In the light of operation types,the study population were divided into two groups,BCT + radiotherapy group and ME group.The X-tile software was used to draw survival curves according to different cut-off point of age.The optimal cut-off point of age was determined when the differences of survival curves were most significant.To control bias and improve the balance between groups as much as possible,the propensity score matching(PSM)was utilized to perform 1:1 matching analysis between BCT group and ME group.Before and after the match,the differences of baseline information between BCT group and ME group were analysis by χ2test.The survival rates,including BCT group and ME group,were separately analysed by Kaplan-Meier method.Log-rank test was used to analyse difference of survival curve between BCT group and ME group.The single-factor and multiple-factor Cox regression was uesd to assess the effect of various research variables on the OS of T1 TNBC patients.Results: On the basis of the study criteria,2082 T1 non-metastatic TNBC patients altogether were screened,including 1644 patients performed BCT +radiotherapy and 438 patients underwent ME.According to X-tile software,the optimal cut-off point of age is 75.So the study population contained two groups,including <75-year-old group and ≥75-year-old group.Between two groups of different surgical types,these follwing study variables were significant differences: age(χ2=49.164,P<0.001),marriage(χ2=14.189,P=0.001),histological grade(χ2=10.343,P=0.016),tumor stage(χ2=71.849,P<0.001),chemotherapy(χ2=19.844,P<0.001).There were more married people in the BCT group than ME group(59.3% VS 49.8%),and the BCT group also had more breast cancer patients at early stage(stage I and IIA)than ME group(97.7% VS 91.5%).The median follow-up time in this study was 34 months(1-83 months).In the entire study population,a total of 198 patients died at the last follow-up,including 122 deaths in the BCT group and 76 deaths in the ME group.In the entire study population,the 2-year OS rate was 96.3% and the5-year OS rate was 88.2%.In the BCT group,the 2-year OS rate was 97.3%and the 5-year OS rate was 90.4%,while the 2-year OS rate was 92.5% and the5-year OS rate was 80.5% in the ME group.According to survival curves between two groups,OS in BCT group was apparently higher than that of in the ME group.Subgroup analysis performed by tumor stage showed that in stage Ⅰ or ⅡA TNBC patients,OS could benefit from BCT(P<0.001;P=0.049),while in stage ⅢA/C patients,no significant difference in OS between the treatment groups was noted(P=0.910).Age(P<0.001),marriage(P=0.004),tumor stage(P=0.002),surgical methods(P<0.001)and chemotherapy(P<0.001)were related with the patients’ OS by univariate Cox regression analysis.Multiple-factor Cox regression indicated that age(P<0.001),tumor stage(P<0.001),surgical methods(P=0.008)and chemotherapy(P=0.003)were associated with overall survival in T1 TNBC patients.After PSM adjusted for confounding factors,a total of 838 patients were involved.Among them,there were 419 cases in the BCT group and 419 cases in the ME group.Baseline information between two groups was basically consistent in general,with no difference.After PSM,single-factor and multiple-factor Cox regression revealed age(P<0.001),tumor stage(P<0.001),surgical methods(P=0.023)and chemotherapy(P=0.013)were critical factors associated with prognosis.Among the 838 patients,a total of 110 patients died at the last follow-up,including 41 deaths in the BCT group and 69 deaths in the ME group.In the BCT group,the 2-year OS rate was 96.8% and the 5-year OS was 86.9%,while the 2-year OS was 93.1% and the 5-year OS was 81.8% in the ME group.Survival curve after PSM indicated that BCT could improve OS of T1TNBC patients.The OS of the BCT group was apparently higher than that of the ME group in the stage Ⅰ patients(P=0.005)by further subgroup analysis,while the OS was no difference in the stage ⅡA or ⅢA/C patients(P=0.170;P=0.540).Conclusion: Stage T1N0-1M0 TNBC and married patients were more likely to accept breast-conserving surgery.Age,tumor stage,surgical methods and chemotherapy were closely related with OS of T1TNBC patients.Breast-conserving surgery and mastectomy were equally safe and effective in patients with T1TNBC,regardless of tumor stage,known as local status of lymph node metastasis.For patients with stage T1N0M0 TNBC,breast-conserving surgery combined with post-operative irradiation were associated with a significantly better prognosis than mastectomy... |
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