The role of cystatin C in multiple myeloma

Introduction Renal insufficiency is one of the common complications in multiple myeloma (MM) and an independent factor indicating a poor prognosis. Cystatin C (Cys C) is considered to be expected to replace creatinine to calculate glomerular filtration rate due to its own characteristics. Gene expression analysis suggested that cystatin C is up-regulated nearly 50-fold in patients with multiple myeloma. Methods To further clarify the role of cystatin C in multiple myeloma, we retrospectively evaluated pretreatment cystatin C levels in 195 newly diagnosed patients through statistical analysis. Results The elevation of serum cystatin C was positively related to the elevation of serum creatinine (P < .001), LDH (P = .006), beta 2-microglobulin (P < .001), bone marrow plasma cell proportion (P = .005) and the reduction of hemoglobin levels (P < .001). Patients with serum cystatin C levels >1.6 mg/L had a significantly shorter progression-free survival (PFS) or overall survival (OS) than patients with serum cystatin C levels <1.6 mg/L (median PFS: median unreached vs 16.7 months, P < .001; median OS: 68 months vs 42 months, P = .014). Although serum cystatin C is not an independent prognostic factor of OS and PFS in patients with multiple myeloma, serum cystatin C can be considered as a sensitive indicator to differentiate well OS and PFS in the group of ISS II patients. Conclusion Serum cystatin C is associated with tumor burden of multiple myeloma and cystatin C can further differentiate the prognosis of ISS II patients. More prospective studies are required to explore the role of serum cystatin C in multiple myeloma.