| Background:In recent years,the incidence of breast cancer is gradually increasing,and the precision treatment of breast cancer is also gaining more and more attention.Among them,human epidermal growthfactor receptor 2(HER2)is the target of targeted drugs for HER2-positive breast cancer.Patients with breast cancer with low HER2 expression(HER2 immunohistochemistry score 1+ or immunohistochemistry score2+,in situ hybridization negative)have low HER2 expression level.Conventional targeted drugs are poorly effective.New targeted drugs can improve the loading rate of HER2 low expressing breast cancer,significantly improve the efficacy of HER2 negative breast cancer,and produce a "bystander effect",thus playing an important role in HER2 low expressing breast cancer.However,there is no standardized treatment for HER2 low expressing breast cancer.Breast cancer is highly heterogeneous,and very little research has been done on HER2 low expressing breast cancer.Therefore,a proper understanding of the pathological features and heterogeneity of HER2 low-expressing breast cancer is important for whether it can be used as a separate breast cancer staging and its treatment.Objective:The aim of this study is to investigate the pathological characteristics of breast cancer with low HER2 expression and the expression and difference of HER2 in primary breast cancer and axillary lymph node metastasis,and to explore the reference value of its changes in guiding clinical treatment,in order to provide relevant evidence for the precise treatment of breast cancer patients with low HER2 expression.Methods:From January 1,2018 to May 31,2022,patients with invasive breast cancer of no special nature diagnosed by pathology in breast and thyroid surgery of our hospital were retrospectively analyzed.HER2 low expression was set as the observation group,and HER2 zero expression and HER2 positive were set as the control group.The clinicopathological characteristics of breast cancer patients with HER2 low expression were analyzed,and breast cancer with axillary lymph node metastasis was selected for immunohistochemical detection to evaluate whether the HER2 expression status was consistent with the primary tumor.The personal data and clinical pathology of the enrolled patients were sorted out and analyzed.Results:1.In all of 202 breast cancer patients were included in the study,covering 70 cases of breast cancer with low HER2 expression,representing 34.7% of all patients,making up 49.3% of HER2-negative breast cancer;There was no transparent discrepancies in age,menstrual status,T stage and pathological stage between HER2 low expression and HER2 zero or HER2 positive((49)> 0.05),but there were significant discrepancies in axillary lymph node metastasis,Ki67 index,histological grade,vascular invasion,estrogen receptor(ER)and progesterone receptor(PR)((49)< 0.05).2.In axillary lymph node metastasis,HER2 low expression was higher than HER2 zero(65.7%vs37.5%,(49)=0.001)and higher than HER2 positive(67.5%vs46.7%,(49)= 0.029),the difference was statistically significant.The proportion of histological grade 2 with low HER2 expression was higher than that with HER-2 zero(72.9%vs58.3%,(49)= 0.007)and HER-2 positive(72.9%vs 53.3 %,(49)< 0.001),and the difference was statistically significant.In patients with vascular invasion,HER2 low expression was higher than HER2 zero(70.0%vs43.1%,(49)= 0.001)and HER2 positive(70.5%vs48.3%,(49)= 0.012),and the difference was statistically significant.In ER positive rate,HER2 low expression was higher than HER2 zero(88.6%vs S66.7 %,(49)= 0.002)and HER2 positive(88.6%vs48.3%,(49)< 0.001),and the difference was statistically significant.In terms of PR positive rate,HER2 low expression was significantly higher than HER2 zero(74.3%vs51.4%,(49)= 0.005)and HER2 positive(74.3%vs 31.7%,(49)< 0.001).The expression level of Ki67 in HER2 low expression was significantly lower than that in HER2 zero((49)=0.005)and HER2 positive((49)< 0.001),and the difference was statistically significant.Among them,Ki67 <15% in HER2 low expression was significantly more than that in HER2 zero expression(34.3%vs22.2%,(49)< 0.05),HER2 positive(34.3%vs5.0%,(49)< 0.001);3.In the comparison of clinicopathological characteristics between HER2 low expression group and HER2 zero group,there were 89 patients with HR+ breast cancer,including 52 cases(58.4%)in HER2 low expression group and 37 cases(41.6%)in HER2 zero group.There were significant differences in axillary lymph node metastasis,pathological stage and vascular invasion rate between the two groups(P<The patients with low HER2 expression had a higher rate of axillary lymph node metastasis,a higher proportion of pathological stage 2,and a higher rate of vascular invasion.However,there were no significant differences in age of onset,menopausal status,T stage,histological grade and Ki-67 index between the two groups.A total of 53 patients with HR-breast cancer were enrolled,including 18 cases(34.0%)in the HER2 low expression group and 35 cases(66.0%)in the HER2 zero group.There were significant differences in T stage,axillary lymph node metastasis,histological grade and Ki67 index between the two groups(P<The HER2 low expression group had a higher rate of axillary lymph node metastasis,a smaller primary tumor,a higher histological grade of G2 stage,and a lower Ki-67 index.However,there were no statistically significant differences in age of onset,menopausal status,pathological stage,and vein invasion between the two groups.4.HER2 expression in the primary foci and lymph node metastases of breast cancer,a total of101 cases were included,46 cases in the HER2 low expression group,among which 11 cases had inconsistent HER2 expression in the primary foci and lymph node metastases of breast cancer,the expression inconsistency rate was 23.9%(11/46),1 case in the HER2 zero group had HER2 expression in lymph nodes different from the primary foci,the expression inconsistency rate was 3.5%(1/27),1 case in the HER2 positive group had HER2 expression in lymph nodes different from the primary foci The expression inconsistency rate was 3.7%(1/27),and the HER-2 positive group had one lymph node with HER2 expression different from the primary foci,and the expression inconsistency rate was 3.5%(1/28),and the difference between the three groups was statistically significant((49)= 0.01).And By comparing the three groups with each other,the differences were statistically significant in both HER2 low expression compared with HER2 positive and HER2 zero groups((49)= 0.024 and(49)= 0.026),and the inconsistency rate was higher in the HER2 low expression group.5.The changes of HER2 expression in primary and lymph node metastases in HER2 low expression breast cancer group did not correlate with patient age,whether menopause,T stage,vascular invasion,ER,PR and Ki-67 values,and the differences were not statistically significant(P > 0.05).The differences were statistically significant when correlated with aspects of tumor N stage,pathological stage,and histological grading((49)< 0.05).Conclusions:1.The rate of axillary lymph node metastasis in HER2 low expressing breast cancer was slightly higher,and there were 23.9%(11/46)of primary and lymph node metastases with different HER2 expression,and the inconsistency rate was higher than HER2 zero and HER2 positive,and their axillary lymph node heterogeneity was higher;2.Lymph node staging,TNM stage,and histological grading were associated with changes in HER2 expression in HER2 low-expressing breast cancer,with higher inconsistency in HER2 expression between the two sites in patients with lymph node stage 2,TNM stage III,and histological grading G2;3.HER2 low expression breast cancer has unique clinicopathological characteristics.The lymph node metastasis rate,histological grade,ER positive rate,PR positive rate and vascular invasion rate of HER2 low expression group are higher than those of HER2 zero expression group and HER2 positive group,and the Ki67 value is lower than that of HER2 zero expression group and HER2 positive group.In addition,the proportion of HR positive in breast cancer patients with low HER2 expression is relatively high.The pathological characteristics of HR positive and HR negative are different,and HR status may affect their pathological characteristics. |
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