Background: Breast cancer (BC) is the most common malignancy in women.
Aim: To assess the impact of HER2 status on axillary lymph node (ALN) involvement in patients with invasive ductal carcinoma of no special type (IDC-NST) both at diagnosis and during the 4-year postoperative period.
Patients and methods: We retrospectively included 375 women with an early clinical stage of non-luminal IDC-NST who between 2007 and 2013 underwent breast surgery at a clinical hospital. They were divided into phenotype-based groups: HR+HER2-, HR+HER2+, HR-HER2+ and HR-HER2-. Only patients with sentinel lymph node (SLN) macrometastases underwent ALN dissection. If > 3 ALNs were positive, radiotherapy was delivered. All patients were treated with chemotherapy, HER2+ BC patients received trastuzumab, and hormone receptor (HR)-positive BC patients received hormonal therapy.
Results: Larger tumor size, higher grade, HR+, HER2+ status, and lymphovascular invasion (LVI) were predictive for ALN metastases at diagnosis. The poorest overall, disease-free, and distant recurrence-free survival (OS, DFS, DRFS) were found in the HR-HER2- group, while the poorest locoregional recurrence-free survival (LRFS) was observed in HR-HER2+ and HR-HER2- groups. HER2 status was not predictor of survival.
Conclusions: HER2+ status was predictive for ALN involvement at diagnosis but had no effect on 4-year LRFS in these patients.