title: Patients with localized and disseminated tumors have reduced but measurable levels of ADAMTS-13 (von Willebrand factor cleaving protease).
abstract: OBJECTIVE
  Patients with disseminated malignancies have been noted to have a deficiency of von Willebrand factor (VWF) cleaving protease, ADAMTS-13. The very low or undetectable plasma levels of this protease are said to be similar to those found in patients with thrombotic thrombocytopenic purpura (TTP). This observation, which challenges the paradigm that severe ADAMTS-13 deficiency is a specific diagnostic marker for TTP, remains so far unconfirmed.
  
  
  METHODS
  We measured the protease and VWF antigen (VWF:Ag) in parallel in 49 Iranian patients with solid tumors, which in 29 cases were localized (stages I and II) and in 20 disseminated (stage IV). Forty-nine healthy individuals matched with cases for sex, age and smoking habits were taken as controls.
  
  
  RESULTS
  Patients with disseminated tumors had lower mean plasma levels of ADAMTS-13 than those with localized tumors, but these differences did not reach the level of statistical significance (p=0.059). However, in no patient was the level of ADAMTS-13 below 18% of normal, at variance with previous findings of lower or unmeasurable levels (<15%). The level of ADAMTS-13 was significantly lower in patients with localized tumors than in controls ( p = 0.0003 ), but higher than in patients with disseminated disease (p=0.0001 vs controls).
  
  
  CONCLUSIONS
  Malignancy, whether localized or disseminated, is another condition associated with low ADAMTS-13 levels not accompanied by signs and symptoms of TTP and other thrombotic microangiopathies.
authors.affiliation: Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Maggiore Hospital and University of Milan, Italy. pmmannucci@libero.it
authors.forename: Pier Mannuccio
authors.initials: PM
authors.lastname: Mannucci
authors.forename: Mehran
authors.initials: M
authors.lastname: Karimi
authors.forename: Ahmad
authors.initials: A
authors.lastname: Mosalaei
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Canciani
authors.forename: Flora
authors.initials: F
authors.lastname: Peyvandi
mesh_terms: D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007492:Iran / Q000453:epidemiology; D008297:Male; D008666:Metalloendopeptidases / Q000097:blood* / Q000172:deficiency; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009369:Neoplasms / Q000201:enzymology* / Q000453:epidemiology / Q000473:pathology*
chemical_list: D051722:ADAM Proteins; D008666:Metalloendopeptidases; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human