Body Composition as a Predictor of Toxicity in Patients Receiving Anthracycline and Taxane-Based Chemotherapy for Early-Stage Breast Cancer.

Poor body composition metrics (BCM) are associated with inferior cancer outcomes; however, in early breast cancer (EBC), there is a paucity of evidence regarding the impact of BCM on toxicities. This study investigates associations between BCM and treatment-related toxicity in patients with EBC receiving anthracyclines and taxane-based chemotherapy. Pretreatment computerized tomographic (CT) images were evaluated for skeletal muscle area (SMA), skeletal muscle density (SMD), and fat tissue at the third lumbar vertebrae. Skeletal muscle index (SMI = SMA/height) and skeletal muscle gauge (SMG = SMI × SMD) were also calculated. Relative risks (RR) are reported for associations between body composition measures and toxicity outcomes, after adjustment for age and body surface area (BSA). BCM were calculated for 151 patients with EBC (median age, 49 years; range, 23-75 years). Fifty patients (33%) developed grade 3/4 toxicity, which was significantly higher in those with low SMI (RR, 1.29; = 0.002), low SMG (RR, 1.09; = 0.01), and low lean body mass (RR, 1.48; = 0.002). Receiver operating characteristic analysis showed the SMG measure to be the best predictor of grade 3/4 toxicity. Dividing SMG into tertiles showed toxicity rates of 46% and 22% for lowest versus highest tertile, respectively ( = 0.005). After adjusting for age and BSA, low SMG (<1,475 units) was significantly associated with hematologic (RR, 2.12; = 0.02), gastrointestinal grade 3/4 toxicities (RR, 6.49; = 0.02), and hospitalizations (RR, 1.91; = 0.05). Poor BCMs are significantly associated with increased treatment-related toxicities. Further studies are needed to investigate how these metrics can be used to more precisely dose chemotherapy to reduce treatment-related toxicity while maintaining efficacy. .