Correlation of Tumor Biology (ER/PR/HER2) With SLN Metastasis

Abstract

Background: Breast cancer is a complex disease, meaning it can have different biological characteristics and spread to other parts of the body. SLNB is a crucial procedure used in the axillary staging of early breast cancer, which is clinically node-negative. Estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) are tumor biology markers that could affect the risk of lymphatic spread.

Objective: To determine the correlation of ER, PR and HER2 status with sentinel lymph node metastasis among patients with Stage I–II invasive breast carcinoma.

Methods: In this descriptive analytical study, 85 women with histologically confirmed Stage I–II invasive breast carcinoma who had sentinel lymph node biopsy were included. The study was conducted at a Tertiary Care Hospital of Rawalpindi, over a period of six months, from January 2026 to June 2026. Patients who received neoadjuvant therapy, had locally advanced breast cancer, had distant metastasis or had recurrent disease were excluded. Data regarding demographic features, tumor stage, tumor grade, lymphovascular invasion, ER status, PR status, HER2 status and sentinel lymph node findings were recorded. Chi-square test or Fisher's exact test was used to determine the association of tumor biology markers with sentinel lymph node metastasis, and logistic regression was used to determine the value of tumor biology markers as predictors of SLN positivity. The p value < 0.05 was regarded as statistically significant.

Results: The mean age of patients was 48.7 ± 10.6 years. Stage II disease was present in 54 patients (63.5%), while Stage I disease was present in 31 patients (36.5%). Sentinel lymph node metastasis was identified in 28 patients (32.9%), whereas 57 patients (67.1%) were SLN-negative. ER-negative tumors showed a higher rate of SLN metastasis than ER-positive tumors (48.3% vs 25.0%, p=0.041). PR-negative tumors were also more frequently associated with SLN positivity than PR-positive tumors (44.4% vs 24.5%, p=0.049). HER2-positive tumors demonstrated the highest SLN positivity rate compared with HER2-negative tumors (52.0% vs 25.0%, p=0.015). SLN metastasis was also significantly associated with Stage II disease, T2 tumor size, Grade III tumors and lymphovascular invasion. On logistic regression, HER2-positive status, ER-negative status, Stage II disease, Grade III tumor and lymphovascular invasion were significant predictors of SLN metastasis.

Conclusion: Sentinel lymph node metastasis was observed in nearly one-third of patients with Stage I–II invasive breast carcinoma. ER-negative, PR-negative and HER2-positive tumors were more frequently associated with SLN involvement. HER2 positivity, ER negativity and lymphovascular invasion were important predictors of sentinel lymph node metastasis. Assessment of tumor biology markers along with clinicopathological features may improve nodal risk stratification in early-stage breast cancer.