Clinicopathological Factors and Interleukin-6 Levels Associated With Low Relative Dose Intensity in Women With Breast Cancer Receiving First-Line Chemotherapy.

BACKGROUND

Chemotherapy has a substantial role in decreasing the risk of recurrence and mortality in breast cancer (BC) in a dose-dependent manner where a low relative dose intensity (RDI) is associated with unfavorable outcomes. Several baseline clinicopathological factors, including pro-inflammatory biomarkers, were found to be significant determinants of low RDI. This study aimed to explore the occurrence of low RDI and its influencing factors in women with BC.

METHODS

This cross-sectional study recruited 172 women with stage I-IV BC who received first-line chemotherapy. We collected patients' clinical, pathological, and treatment data and analyzed the pre-chemotherapy C-reactive protein (CRP) and interleukin (IL)-6 levels using a quantitative enzyme-linked immunosorbent assay (ELISA). We calculated the RDI based on the actual and planned delivered chemotherapy dose (mg/m) and duration (weeks). RDI less than 85% was defined as "low". Multivariate analysis with logistic regression was conducted to determine the association between pre-chemotherapy parameters and RDI < 85%.

RESULTS

The mean CRP level was 10.82 ± 19.17 mg/L (0.00 - 151.73 mg/L) and the mean IL-6 level was 1.12 ± 3.41 pg/mL (0.00 - 27.67 pg/mL). The average RDI for all patients was 93±8.19%. An RDI < 85% occurred in 23 patients (13.4%). The presence of diabetes mellitus (odds ratio (OR): 4.78, 95% confidence interval (CI): 1.03 - 22.27, P = 0.046), triple-negative tumors (OR: 6.45, 95% CI: 1.39 - 29.83, P = 0.017), and IL-6 levels > 0.5 pg/mL (OR: 3.45, 95% CI: 1.01 - 11.79, P = 0.049) was associated with an increased low RDI risk.

CONCLUSION

The proportion of BC patients receiving a low chemotherapy RDI in our study was comparable to published literature and drove close monitoring of patients at risk to provide adequate management.