| Objective:To compare the clinicopathological features,sentinel lymph node(SLN)metastasis and prognosis of patients with different human epidermal growth factor receptor 2(HER-2)protein expression in early breast cancer,and to provide clinical evidence for whether low HER-2 expression breast cancer can be used as an independent biological subtype.Methods:The clinicopathological data of 792 cases of early breast cancer patients admitted to the Department of Thyroid and Breast Surgery,Affiliated Hospital of Inner Mongolia Medical University from June 2010 to June 2019,and the patients were divided into three groups according to HER-2 protein expression levels: HER-2 non-expression(HER-2 IHC 0),low HER-2 expression(HER-2 IHC 1+,HER-2 IHC 2+ and ISH negative),and HER-2 positive(HER-2 IHC 2+ and ISH positive,HER-2 IHC 3+).The differences in clinicopathological features,SLN metastasis and prognosis among different HER-2 subgroups were retrospectively analyzed.Results:1.Patients with low HER-2 expression were mainly luminal A,and triple-negative breast cancer(TNBC)accounted for a lower proportion;compared with patients with HER-2non-expression,patients with low HER-2 expression had a higher proportion of axillary lymph node positivity,vascular cancer embolus and HR +,and a lower proportion of invasive lobular carcinoma,histological grade and high Ki-67 expression;and after stratification by HR status,only pathological type(P=0.004)and histological grade(P=0.035)were statistically different in the HR + group,and no statistically significant differences were observed in the clinicopathological features of all patients in the HR-group.2.Among the 792 breast cancer patients,528(66.7%)cases were SLN negative and 264(33.3%)cases were SLN positive.Among the 264 SLN positive patients,69(26.1%)cases were HER-2 non-expression,97(36.8%)cases were low HER-2 expression,and 98(37.1%)cases were HER-2 positive.Compared with patients with HER-2 non-expression,SLN metastasis rates were significantly increased in patients with low HER-2 expression(P=0.019)and HER-2 positive patients(P<0.001).Using HER-2 non-expression breast cancer as a reference,low HER-2 expression breast cancer had a 1.545-fold increased risk of SLN metastasis(95% CI: 1.041 to 2.293,P=0.019)and HER-2 positive breast cancer had a3.880-fold increased risk of SLN metastasis(95% CI: 2.026 to 7.430,P<0.001).3.A total of 792 patients were followed up until June 2022,including 89 cases of disease recurrence or distant metastasis and 40 deaths(33 breast cancer-related deaths and 7non-breast cancer-related deaths).Follow-up ranged from 7 to 149 months,with a median follow-up of 56 months.The 5-year DFS was 92.9% and 91.3%,and the 5-year OS was97.4% and 96.8% in patients with low HER-2 expression and HER-2 non-expression,respectively,and log-rank test analysis showed that there were no statistically significant differences in 5-year DFS(P=0.206)and 5-year OS(P=0.288)between patients with low HER-2 expression and HER-2 non-expression,and there was no significant difference after stratified analysis according to HR status.Conclusions:1.In low HER-2 expression breast cancer,the positive rate of axillary lymph nodes,vascular cancer embolus and HR+ were higher,and the proportion of invasive lobular carcinoma,histological grade III and high Ki-67 expression was lower.2.Low HER-2 expression and HER-2 positive breast cancers had an increased risk of SLN metastasis compared to HER-2 non-expression breast cancers.3.Regardless of HR status,there was no statistically significant difference in 5-year DFS and 5-year OS between low HER-2 breast cancer patients and HER-2 non-expression breast cancer patients,although low HER-2 expression breast cancer has unique clinicopathological features,there is only a slight difference in survival between the two groups and no statistical significance,so this study does not support that low HER-2 breast cancer can be used as an independent biological subtype. |
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