Effect of muscle mass on toxicity and survival in patients with colon cancer undergoing adjuvant chemotherapy

Purpose: The purpose of this study was to elucidate the effect of decreased muscle mass on the toxicity and survival of patients with colon cancer treated with adjuvant chemotherapy after surgery.Methods: We reviewed the data of 229 consecutive patients with stage III colon cancer who received adjuvant oxaliplatin, 5-fluorouracil, and leucovorin chemotherapy at a single center between 2003 and 2010. Baseline muscle mass was assessed by measuring the cross-sectional area of the psoas muscle at the level of the fourth lumbar vertebra on computed tomography images. Effects of muscle mass on toxicity of chemotherapy and survival were assessed.Results: The median age of the 229 patients was 61 years (range, 28–80) and 134 (58.5 %) were men. The mean psoas muscle mass index (PI, psoas muscle area divided by height² [mm²/m²]) was 548.3. A 1 SD decrement in the PI was associated with an increase in all grade 3–4 toxicities in univariate (OR = 1.69, 95 % CI = 1.18–2.27) and multivariate (OR = 1.56, 95 % CI = 1.05–2.38) analyses. In univariate analysis, the PI was not associated with overall survival. However, multivariate analysis showed that a 1 SD decrement in the PI increased the hazard of overall mortality by 85 % (HR = 1.85, 95 % CI = 1.10–3.13). This effect of the PI on mortality was maintained in subgroup analyses, especially in older and obese patients.Conclusions: Decreased muscle mass was associated with increased risk of grade 3–4 toxicity and poor prognosis in patients with stage III colon cancer.