On Relationship Between Molecule Subtypes Of Invasive Lobular Carcinoma And Axillary Lymph Node Metastasis

Objective To explore the related factors of the axillary lymph node metastasis and identify the relationship between molecular subtype and axillary lymph node metastasis through a retrospective analysis of clinical and pathological data of 65 cases invasive lobular carcinoma.Method The clinical and pathological data of 65 pure breast invasive lobular carcinomas and 242 pure invasive ductal carcinomas from January 2011 to December 2015 in Breast Surgery of China-Japan union hospital of Jilin university were retrospectively analyzed. We compared the difference of axillary lymph node metastasis between invasive lobular carcinoma(ILC) and invasive ductal carcinoma(IDC). According to the results of estrogen receptor(ER), progesterone receptor(PR), human epidermal growth factor receptor 2(HER2) and Ki67 in immunohistochemistry(IHC) test, 65 patients of ILC were divided into Luminal A(ER + and/or PR +, HER2-, Ki67 < 14%), Luminal B(HER2 negative: ER + and/or PR +, HER2- and Ki67≥14%; HER2 positive: ER + and/or PR +, HER2+ and Ki67 at any level), HER2 over expression type(ER and PR-, HER2 +) and Basal-like type(ER-, PR-, HER2-).Then we compared the difference of the axillary lymph node metastasis of four molecular subtypes and analyzed the effect of tumor size, age, menstrual status, Ki67, E-cad and HER2 on the axillary lymph node metastasis of ILC.Results Age of ILC patients in the study range from 28 to 75 years old, and the median age is 48 years. T2 is the most common tumor size in ILC and accounts for 46.2%. The rate of axillary lymph node metastasis(47.7%) in ILC is larger than that in IDC(35.1%), and the difference of the rate between ILC and IDC has statistical significance. In the distribution of subtype of the ILC, Luminal A accounts for 41.5%, Luminal B accounting for 48.5%(including HER2-negative accounting for 24.6%; HER2-positive accounting for 13.9%), HER2 over expression type accounting for 7.7%, and Basal-like type accounting for 12.3%.Among the four subtypes, Luminal A has the most cases and HER2 over expression type has the least. Luminal B type(HER2-negative) had the highest axillary lymph node metastasis rate(75.0%), followed by HER2 over expression type(60%), Luminal B type(HER2-positive)(55.6%), Basal-like type(37.5%), and Luminal A type(29.6%). The difference among the four molecular subtypes is statistically significant(P<0.O5).The rate of the positive axillary lymph nodes in Ki67 high expression group(68.4%) is significantly higher than that in Ki67 low expression group(39.1%), and the difference is statistically significant(χ2=4.62; P=0.03). The axillary lymph node metastasis rate increases significantly when the tumor size is over 5 cm, and the difference is statistically significant(P<0.01). The rate of the positive axillary lymph nodes in HER2 positive group is higher than that in HER2 negative group. The rate of the axillary lymph node metastasis in E-cad positive group is higher than that in E-cad negative group. There is no statistically significant difference between age/menstrual status and axillary lymph node metastasis.Conclusion In ILC, the difference of the rate of axillary lymph node metastasis among the four molecular subtypes is statistically significant. Molecular subtype is a factor which can affect axillary lymph node metastasis in ILC. The rate of axillary lymph node metastasis in ILC is larger than that in IDC, and the difference of the rate between ILC and IDC has statistical significance. Ki67 is an important factor which can affect axillary lymph node metastasis in ILC. The high expression Ki67 has more adverse effect on the axillary lymph node metastasis, so the adjuvant chemotherapy should be paid more attention in ILC patients with Ki67 high expression and largely applied in such patients. HER2 positive may contribute to more aggression in ILC. HER2 targeting therapy is crucial for the patients with HER2 positive. Tumor size is an important factor of axillary lymph node metastasis in ILC. Age and menstrual status of patients in ILC have no obvious correlation with axillary lymph node metastasis.