Impact of Molecular Subtypes of Breast Cancer on Axillary Lymph Node Metastasis: A Tertiary Center Experience

Background: Axillary lymph node metastasis (ALNM) is one of the important prognostic factors of breast cancer. The objective of this study was to assess the risk of ALNM in different molecular subtypes determined by estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor ۲ (HER۲Neu) of breast cancer.Methods: This retrospective study was conducted on patients who had undergone upfront breast conserving surgery (BCS) or modified radical mastectomy (MRM). Patients were classified as HR (hormone receptor)+/ HER۲Neu- (ER or PR positive and HER۲Neu negative), HR+/HER۲Neu+ (ER or PR positive and HER۲Neu positive), HR-/HER۲Neu- (ER, PR and HER۲Neu negative or triple negative or basal type), and HR-/HER۲Neu+ (ER or PR negative and HER۲Neu positive). The association between clinicopathological variables and ALNM was evaluated in logistic regression analyses.Results: In this study, ۴۷۶ patients met the inclusion criteria, and had ۶۷.۲% ALNM at diagnosis. ALNM was statistically significantly correlated with age ≤ ۴۰ years (P=۰.۰۲۶), tumor grade (P=۰.۰۰۷), pathological tumor size (P<۰.۰۰۱), estrogen receptor (P=۰.۰۴۵), molecular subtypes (P=۰.۰۲۱), LVI (P<۰.۰۰۱), and PNI (P<۰.۰۰۱). Post Hoc test revealed that HR-/HER۲Neu+ subtypes of breast cancer had the highest and HR+/HER۲Neu- had the lowest risk of ALNM.Conclusion: ALNM may be predicted by molecular subtypes of breast cancer. The risk of ALNM is less in TNBC although it is clinically more aggressive. These findings may play an important role in gauging the individualized axillary management in breast cancer.

Keywords:

molecular subtypes , breast cancer , axillary lymph node , metastasis