Serum levels of cystatin C in elderly lung cancer patients.

The purpose of this study was to confirm the correlation between serum levels of cystatin C (Cys-C) and those of creatinine (Cre), the most widely used index of renal function in clinical practice, and to evaluate serum levels of Cys-C, with a particular focus on the effects of aging, body mass index (BMI), C-reactive protein (CRP) and disease extent in patients with lung cancer. Serum Cys-C levels in a total of 39 patients (median 72 years), who were diagnosed as having lung cancer were analyzed retrospectively. The serum Cys-C was determined using colloidal gold particles coated with anti-Cys C antibodies. A significant correlation coefficient was found between serum levels of Cys-C and those of Cre (P=0.001), but only moderate agreement. Serum Cys-C levels increased in an age-dependent manner with significant differences among 3 age groups: patients younger than 65 years, those aged 65 to 74 years and those aged 75 years or older (P=0.001). However, no correlation was observed between Cys-C and BMI, Cys-C and CRP, or Cys-C and disease extent of lung cancer. Estimation of renal function is important since renal insufficiency is directly correlated to increased chemotherapeutic complications in oncological practice. Thus, estimation of serum Cys-C levels may be important, but adjustment of Cys-C for age should be taken into consideration.