A New Index Based on Serum Creatinine and Cystatin C is Useful for Assessing Sarcopenia in Advanced Cancer Patients

Abstract Purpose Sarcopenia is a well-known risk factor for inferior cancer outcomes, but the identification of patients at risk remains challenging. A new sarcopenia index (SI), defined as serum creatinine (Cr) × cystatin C (CysC)-based glomerular filtration rate (eGFRCysC), has been reported to be an objective surrogate marker for sarcopenia. We aimed to assess whether the SI is associated with sarcopenia and cancer-related fatigue (CRF) in advanced cancer patients. Methods A total of 182 patients with different types of cancer (cancer stages III/IV; mean age 55.1 ± 11.1 years) were enrolled in this cross-sectional study. Sarcopenia was defined as the presence of both low muscle mass and low muscle strength. The cross-sectional area of skeletal muscle mass (SMA) at the third lumbar spine was estimated by computed tomography (CT). Low muscle mass was defined as a skeletal muscle index (SMA/height2) less than 34.9 cm2/m2 for females and 40.8 cm2/m2 for males. Low muscle strength was determined by handgrip strength (HGS) according to the cutoffs of the Asian Working Group for Sarcopenia ( Results The prevalence of sarcopenia was 27.5%. The SI was significantly lower in both the sarcopenia and severe fatigue groups. The associations between SI and SMA (r = 0.365; P Conclusion The SI might be a useful objective tool for assessing sarcopenia in advanced cancer patients. Further studies are warranted to extend our findings.