Association Between Peripheral Blood Lymphocyte Count and HER2 Status in Breast Cancer: A Retrospective Study.

Area of Science:

• Oncology
• Immunology
• Biomarkers

Background:

• HER2 overexpression in breast cancer correlates with aggressive disease and unique immune microenvironments.
• The relationship between peripheral absolute lymphocyte count (ALC) and HER2 status is not well understood.

Purpose of the Study:

• To investigate the association between pretreatment peripheral ALC and HER2 status in breast cancer patients.
• To explore the implications of this association for systemic and tumor-specific immunity.

Main Methods:

• Retrospective analysis of breast cancer patient data.
• Multivariate logistic regression, random forest, and restricted cubic spline analyses.
• Tumor immune infiltration profiling using TIMER 2.0.

Main Results:

• A consistent inverse association was found between ALC and HER2-positive status.
• Higher ALC was independently linked to lower odds of HER2 positivity (OR=0.53).
• HER2 expression negatively correlated with anti-tumor lymphocytes (CD8+ T cells, NK cells) and enriched immature B cells.

Conclusions:

• Peripheral ALC is negatively correlated with HER2 expression in breast cancer.
• Accessible ALC can serve as a complementary indicator for HER2-related immune characteristics and heterogeneity.