Skeletal Muscle Measures as Predictors of Toxicity, Hospitalization, and Survival in Patients with Metastatic Breast Cancer Receiving Taxane Based Chemotherapy

Abstract

Purpose

Severe skeletal muscle (SM) loss (sarcopenia), is associated with poor cancer outcomes including reduced survival and increased toxicity. This study investigates SM measures in metastatic breast cancer (MBC) patients receiving first line taxane-based chemotherapy and evaluates associations with treatment toxicity and other outcomes.

Experimental Design

Using computerized tomography (CT) images taken for the evaluation of disease burden, skeletal muscle area (SMA) and density (SMD) were measured at the 3rd lumbar vertebrae. Sarcopenia was defined as Skeletal Muscle Index (SMI=SMA/height ²) ≤41. Skeletal Muscle Gauge (SMG) was created by multiplying SMI x SMD. Fisher’s exact tests, t-tests, the Kaplan-Meier method, and Cox regression modeling were used.

Results

MBC patients (N=40), median age 55 (rang 34–80), 58% sarcopenic, median SMG 1296 AU (SD 522). Grade 3–4 toxicity was found in 57% of sarcopenic vs 18% of non-sarcopenic patients ( p=0.02). Toxicity-related hospitalizations were also higher in sarcopenic patients (39% vs 0%, p=0.005) as were any adverse events -- defined as any grade 3–4 toxicities, hospitalizations, dose reductions, or dose delay -- (74% vs 35%, p=0.02). Low SMG was associated with grade 3–4 toxicity ( p=0.04), hospitalization ( p=0.01) and time to treatment failure (for progression or toxicity) ( p=0.03). Low SMG had a borderline significant association with any adverse event ( p=0.06) and overall survival ( p=0.07).

Conclusions

SM measures are associated with toxicity outcomes and survival in MBC patients receiving first line taxane-based chemotherapy. Further studies are needed to explore how routinely obtained CT scans can be used to individualize dosing and improve treatment planning.