title: Improved prediction of decreased creatinine clearance by serum cystatin C: use in cancer patients before and during chemotherapy.
abstract: BACKGROUND
  Serum cystatin C, a cysteine protease inhibitor, has been suggested as a new marker of glomerular filtration rate (GFR). This study explored the possibility of replacing the creatinine clearance (CrCl) estimation of GFR with cystatin C in early detection of renal impairment in cancer patients on chemotherapy.
  
  
  METHODS
  Serum creatinine and cystatin C concentrations as well as 24-h CrCl were determined simultaneously in 72 cancer patients. Among them, 60 were treated with combined chemotherapy with cisplatin (CDDP). Creatinine was determined enzymatically with a spectrophotometric method. Serum cystatin C was determined by a particle-enhanced turbidimetric immunoassay.
  
  
  RESULTS
  Cystatin C and creatinine correlated significantly (P = 0.001) with CrCl. The correlation was significantly better for cystatin C than creatinine (r = 0.84 vs 0.74; P = 0.01). Stepwise regression analysis identified no differences for the correlations between cystatin C and CrCl in patients with or without metastases (r = 0.82 and 0.84, respectively) as well as before treatment and before the fourth cycle of chemotherapy (r = 0.70 and 0.75, respectively). A cystatin C cutoff concentration of 1.33 mg/L had 87% sensitivity and 100% specificity for detecting CrCl <78 mL/min. ROC analysis indicated that cystatin C was superior to serum creatinine for predicting CrCl <78 mL/min (P <0.04).
  
  
  CONCLUSIONS
  Serum cystatin C is superior to serum creatinine for detection of decreased CrCl and potentially for the estimation of GFR in cancer patients independent of the presence of metastases or chemotherapy.
authors.affiliation: Institute of Oncology, Zaloska 2, 1000 Ljubljana, Slovenia. Faculty of Medicine, Vrazov trg 4, 1000 Ljubljana, Slovenia. bstabuc@onko-i.si
authors.forename: B
authors.initials: B
authors.lastname: Stabuc
authors.forename: L
authors.initials: L
authors.lastname: Vrhovec
authors.forename: M
authors.initials: M
authors.lastname: Stabuc-Silih
authors.forename: T E
authors.initials: TE
authors.lastname: Cizej
mesh_terms: D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use; D002945:Cisplatin / Q000627:therapeutic use; D003404:Creatinine / Q000097:blood*; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008545:Melanoma / Q000097:blood* / Q000188:drug therapy / Q000473:pathology; D008875:Middle Aged; D009362:Neoplasm Metastasis; D010051:Ovarian Neoplasms / Q000097:blood* / Q000188:drug therapy / Q000473:pathology; D012680:Sensitivity and Specificity; D013274:Stomach Neoplasms / Q000097:blood* / Q000188:drug therapy / Q000473:pathology
chemical_list: D000970:Antineoplastic Agents; C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D003404:Creatinine; D002945:Cisplatin