Loss of Muscle Mass During Chemotherapy Is Predictive for Poor Survival of Patients With Metastatic Colorectal Cancer

Low muscle mass is present in approximately 40% of patients with metastatic colorectal cancer (mCRC) and may be associated with poor outcome. We studied change in skeletal muscle during palliative chemotherapy in patients with mCRC and its association with treatment modifications and overall survival. In 67 patients with mCRC (mean age ± standard deviation, 66.4 ± 10.6 years; 63% male), muscle area (square centimeters) was assessed using computed tomography scans of the third lumbar vertebra before and during palliative chemotherapy. Treatment modifications resulting from toxicity were evaluated, including delay, dose reduction, or termination of chemotherapy. Multiple regression analyses were performed for the association between change in muscle area and treatment modification and secondly overall survival. Muscle area of patients with mCRC decreased significantly during 3 months of chemotherapy by 6.1% (95% CI, -8.4 to -3.8; P <.001). Change in muscle area was not associated with treatment modifications. However, patients with muscle loss during treatment of 9% or more (lowest tertile) had significantly lower survival rates than patients with muscle loss of less than 9% (at 6 months, 33% v 69% of patients alive; at 1 year, 17% v 49% of patients alive; log-rank P = .001). Muscle loss of 9% or more remained independently associated with survival when adjusted for sex, age, baseline lactate dehydrogenase concentration, comorbidity, mono-organ or multiorgan metastases, treatment line, and tumor progression at first evaluation by computed tomography scan (hazard ratio, 4.47; 95% CI, 2.21 to 9.05; P <.001). Muscle area decreased significantly during chemotherapy and was independently associated with survival in patients with mCRC. Further clinical evaluation is required to determine whether nutritional interventions and exercise training may preserve muscle area and thereby improve outcome