title: Serum cystatin C in patients with head and neck carcinoma.
abstract: BACKGROUND
  The balance between proteinases of various classes and their inhibitors was found to be of critical importance for local invasion and metastasizing of tumor cells. The aim of the present study was to determine the changes in the serum cystatin C concentration in patients with squamous cell carcinoma of the head and neck.
  
  
  METHODS
  In the sera of 34 patients with squamous cell carcinoma of the head and neck, the concentration of cysteine proteinase inhibitor cystatin C was determined using ELISA. The serum samples were collected at diagnosis (group A) and 7 to 407 days (median, 59 days) after the therapy (group B). The sera of 30 healthy blood donors served as controls (group C).
  
  
  RESULTS
  A significant increase in the median concentration of cystatin C was found in the patients' sera (group A: 573 ng/ml, P<0.0001; group B: 551 ng/ml, P<0.0001) compared to control group C (320 ng/ml), whereas no difference was observed between groups A and B (P>0.05). Cystatin C concentrations in the sera of group A correlated with the site of primary tumor (P=0.035), being higher in the patients with non-laryngeal tumors (658 ng/ml) than in those with larynx primaries (529 ng/ml). There was a significant trend (RS=-0.535, P=0.049) towards lower cystatin C concentrations with an increasing time delay in post-treatment serum sampling (group B), which was observed in the patients with no relapse of the disease and a sampling later than 45 days after the completion of therapy.
  
  
  CONCLUSIONS
  These results add to the knowledge of the role of cystatin C in invasive behavior of squamous cell carcinoma of the head and neck, and suggest its potential role as a tumor marker in this particular type of cancer.
authors.affiliation: Department of Radiation Oncology, Institute of Oncology, Zaloska 2, SI-1000 Ljubljana, Slovenia.
authors.forename: Primoz
authors.initials: P
authors.lastname: Strojan
authors.forename: Branka
authors.initials: B
authors.lastname: Svetic
authors.forename: Lojze
authors.initials: L
authors.lastname: Smid
authors.forename: Janko
authors.initials: J
authors.lastname: Kos
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood; D016022:Case-Control Studies; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D005260:Female; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000097:blood / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000175:diagnosis; D012008:Recurrence
chemical_list: D014408:Biomarkers, Tumor; C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins