# CRP, NLR, and PLR Dynamics in Non‐Metastatic Breast Cancer Patients Receiving Chemotherapy: Associations With Nutritional and Clinical Factors

## TL;DR

This study examines how inflammatory biomarkers change during chemotherapy in breast cancer patients and finds that CRP remains elevated while BMI is linked to higher CRP levels.

## Contribution

The study provides new insights into the dynamics of CRP, NLR, and PLR during chemotherapy and their associations with nutritional and clinical factors.

## Key findings

- CRP remained elevated in most patients and showed moderate temporal stability between chemotherapy cycles.
- BMI was significantly associated with higher CRP levels after adjustment for other factors.
- NLR and PLR showed modest upward trends but changes were not statistically significant after adjustment.

## Abstract

Systemic inflammatory biomarkers such as C‐reactive protein (CRP), neutrophil‐to‐lymphocyte ratio (NLR), and platelet‐to‐lymphocyte ratio (PLR) are increasingly studied in breast cancer, but their within‐treatment dynamics and relationship with anthropometric context during chemotherapy remain underexplored. This study aimed to evaluate early‐to‐intermediate, within‐treatment changes in inflammatory biomarkers (CRP, NLR, PLR) and examine their associations with sociodemographic, clinical, and anthropometric variables among women with stage I–III non‐metastatic breast cancer receiving outpatient chemotherapy, measured immediately before the first (C1) and third (C3) cycles.

Prospective single‐arm cohort of women with stage I–III breast cancer receiving outpatient chemotherapy at a single center. Biomarkers were measured immediately before the first infusion (C1) and before the third cycle (C3). Nutritional status was assessed anthropometrically (BMI, waist circumference, triceps skinfold thickness, arm circumference, corrected arm muscle area). Primary analyses modeled biomarkers as continuous outcomes in linear mixed models (LMMs) including time (C1 vs. C3) and covariates significant in bivariate tests; effect sizes were estimated using Glass's Delta. We also assessed pairwise correlations among biomarkers within C1 and C3 and temporal stability (C1 ↔ C3) using Spearman's rho with FDR control.

CRP was elevated in 26/30 (86.7%) at C1 and remained high at C3; the time effect was not significant in adjusted models (ANOVA p = 0.951). Mean NLR and PLR were below common clinical thresholds at both time points but trended upward; PLR increased in crude paired testing (p = 0.049), yet the adjusted time effect was not significant (p = 0.468). Effect sizes were tiny for NLR (Δ = 0.08) and CRP (Δ = 0.007) and small for PLR (Δ = 0.20). In multivariable analyses, BMI remained associated with higher CRP (ANOVA p = 0.012). Inter‐marker correlations within C1 and C3 were small and not significant after FDR adjustment. CRP showed moderate temporal stability between C1 and C3 (ρ = 0.628; q = 0.003), whereas NLR (ρ = 0.327; q = 0.300) and PLR (ρ = 0.325; q = 0.300) were positive but not statistically significant.

Early within‐treatment monitoring revealed a stable elevation of CRP and modest upward trends in NLR/PLR from C1 to C3, with BMI associated with CRP after adjustment. CRP also exhibited greater short‐term stability than NLR/PLR. Although limited by small sample size and two time points, these findings are hypothesis‐generating and support larger, multi‐center studies with denser sampling and longer follow‐up to clarify prognostic value and inform personalized supportive care.