Monitoring of renal function in cancer patients:: an ongoing challenge for clinical practice

Background: Renal impairment (RI) has been shown to be one major risk factor in a number of diseases and is associated with a dismal clinical outcome. However, the influence of milder degrees of renal disease is less well defined, particularly not in patients with malignant diseases. Patients and methods: We analyzed 167 patients with solid tumors and hematological malignancies. Besides disease-specific parameters, serum creatinine, cystatin C and the estimated glomerular filtration rate (eGFR) ['modification of diet in renal disease' equation (MDRD)/Cockcroft-Gault (CG)] were determined. Patients were compared within eGFR, creatinine and cystatin C groups. Results: The median MDRD, CG, creatinine and cystatin C levels of all patients were 88 ml/min/1.73 m(2), 89 ml/min, 1 mg/dl and 0.9 mg/l, respectively. Patients with chronic kidney disease stage 2 still showed normal creatinine and cystatin levels of 1 mg/dl and 1.1 mg/l, respectively, although mild RI was frequent. Those cancer patients with decreased eGFR (MDRD) (<60 ml/min/1.73 m(2)) had increased odds ratios (ORs) to have more concurrent diagnoses [OR 3.4; 95% confidence interval (Cl) 1.5-8.1], a body mass index >24 kg/m(2) (OR 2.1; 95% Cl 1.0-4.5) and an elevated (>245 pg/ml) pro-brain natriuretic peptide level (proBNP) (OR 9.2; 95% Cl 3.0-28.3). Conclusions: These observations suggest that grouping cancer patients according to renal function, especially eGFR, may be one way to determine specific risk groups.