The role of breast cancer molecular subtypes in axillary lymph node positivity.

Breast cancer is a complex disease with various histopathological and molecular features. We aimed to investigate the clinicopathological predictor factors, especially molecular sub-types, on axillary involvement in breast cancer patients. Female patients who underwent mastectomy or breast-conserving surgery combined with sentinel lymph node biopsy or axillary dissection were included in this study. Clinicopathological features including age, tumor location, lymphovascular invasion, perineural invasion, grade, tumor size, and hormonal receptor status were recorded. The cohort consisted of 238 patients. The mean age of the participants was 55.24±11.52 years. The most common molecular sub-type was Luminal B HER2-with 30.3%. This sub-type was followed by Triple-Negative (22.7%), Luminal A (18.9%), non-Luminal HER2+ (16.4%), and Luminal B HER2+ (11.8%), respectively. There was a significant relationship between the tumor sub-type and the axillary involvement (p=0.003). Axillary lymph node metastases were less common in Luminal A and Triple-Negative tumors. In luminal A sub-type, axillary involvement was the lowest with a rate of 24.4% (OR=0.260, 95%Cl: 0.124-0.543, p<0.001). In contrast, Luminal B HER2+ and non-Luminal HER2+ sub-types were highly positive in terms of axillary involvement. Luminal B HER2+ sub-type had the highest rate (60.7%). Luminal A, Triple-Negative tumors had a decreased risk of lymph node positivity as compared to other sub-types. Molecular subtypes should be regarded as an important factor affecting the condition of the axilla. [ABSTRACT FROM AUTHOR]