The Predictive Value For Axillary LN Metastasis With Immunohistochemistry-based Molecular Subtypes Of Breast Cancer

Objective: To study the correlation between immunohistochemistry-basedmolecular subtypes of breast cancer and axillary lymph node metastasis status, andanalyse the correlation between axillary LN metastasis and age, histology, tumor size，discussing the predictive value for axillary LN metastasis withimmunohistochemistry-based molecular subtypes of breast cancer.Methods: A regression analysis was made on669cases of breast cancer patientsreceiving surgical therapy in Liaoning Cancer Hospital from January2006to October2006.271cases were chose which were pathological diagnosed with non carcinoma insitu (non DCIS or LCIS), no neoadjuvant chemotherapy before, first surgical therapy forbreast cancer and with complete clinical data. These cases were classified into fourmolecular subtypes：1. Luminal A (ER and PR positive，HER-2negative，Ki-67low)；2. Luminal B（HER-2negative)（ER positive，HER-2negative， at least one of PRnegative or low or Ki-67high)、Luminal B（HER-2positive)（ER positive，HER-2over-expressed or amplified，Any Ki-67，Any PR)；3. HER-2-enriched (HER-2over-expressed or amplified，ER and PR absent)；4. Basal-like（Triple negative）（ERand PR absent， HER-2negative)， according to the results ofIHC(ER/PR/HER-2/Ki-67). The statistics were made by SPSS20.0in this study. χ2test and Fisher exact test were used to analyze the associations between patients’ pathological characteristics and axillary LN status and different molecular subtypes.Multinomial logistic regression was used to analyze the influencing factors with axillaryLN metastasis.Results: In271cases, about half patients’ age were less than50, about80%patients’ histological grade were IDC (infitrating ductal carcinoma). Cases wereclassified by molecular subtype: Luminal B (HER-2negative):27.3%, Luminal A:22.88%, Basal-like:22.14%, Luminal B (HER-2positive):19.19%,HER-2over-expression:8.49%.Different molecular subtype came different LN positivity: thehighest were Luminal B (HER-2positive):80.77%. HER-2over-expression, Luminal B(HER-2negative), Basal-like were less, and the lowest were Luminal A:30.64%.Therefore, there were statistical significances between molecular subtype and LNpositivity. As for age, histological grade and tumor size, patients (age<50and tumormaximum diameter≤2cm) had a higher positivity than those who (age≥50and tumormaximum diameter>2cm). Logic regression analysis shows that age, tumor size andmolecular subtype are independent factors for axillary LN metastasis, of which LuminalB (HER2+) subtype has higher risk of LN positivity than Luminal A subtype, HER2over-expression has higher risk of LN positivity than Luminal A subtype.Conclusions: Immunohistochemistry-based molecular subtypes are associatedwith axillary lymph node metastasis of breast cancer. Luminal B subtype expressedHER-2(HER2positive), HER-2over-expression subtype have the characteristics ofhigh rate of axillary lymph node metastasis, which is the independent factor predictingaxillary lymph node metastasis of breast cancer.