Peripheral Absolute Lymphocyte Count, Breast Cancer-Specific and Overall Mortality According to Race, Ethnicity, and...

Area of Science:

• Oncology
• Hematology
• Epidemiology

Background:

• Low absolute lymphocyte count (ALC) is a known predictor of mortality in non-Hispanic White women with triple-negative breast cancer (TNBC).
• The association between ALC and mortality in other breast cancer subtypes and racial/ethnic groups remains largely unexplored.

Purpose of the Study:

• To investigate the relationship between ALC and breast cancer-specific mortality (BCM) and overall mortality (OM) across different breast cancer subtypes.
• To evaluate whether race or ethnicity modifies the association of ALC with BCM and OM.

Main Methods:

• Utilized the Oncoshare database, linking electronic medical records with the California Cancer Registry for women diagnosed with stage I-III breast cancer (2000-2017).
• Employed logistic regression to identify factors associated with low ALC (<1 K/µL) and Cox models to assess the association of minimum ALC (minALC) with BCM and OM.

Main Results:

• In 11,669 women, low ALC correlated with neutropenia, chemotherapy, advanced stage, comorbidities, and aggressive tumor features.
• Lower minALC was associated with higher OM (HR=0.96), with a stronger association in TNBC (HR=0.73).
• Significant interactions (p<0.001) indicated that race and ethnicity modified the minALC-mortality associations, being stronger in NH Black and Hispanic women compared to NH White women.

Conclusions:

• Low peripheral ALC is associated with increased overall mortality in women with estrogen/progesterone receptor-positive, HER2-negative breast cancer or TNBC.
• The association between low ALC and mortality is more pronounced in women from minoritized racial and ethnic groups.