title: Activated-protein-C resistance in cancer patients.
abstract: BACKGROUND
  Resistance to activated protein C (aPC) is usually linked to factor V Leiden, but may occur in other disorders associated with hypercoagulability. In this study, we investigated the frequency of resistance to aPC in patients with advanced cancer and examined the relationship of aPC resistance to other markers of coagulation activation.
  
  
  METHODS
  Patients (n = 39) had established diagnosis of advanced cancer; controls (n = 20) were healthy persons. aPC resistance was measured as the ratio of activated partial thromboplastin times with and without aPC (aPC-sensitivity ratio, aPC-SR). The factor V Leiden mutation was detected by a polymerase-chain-reaction based technique. Other assays were performed by standard laboratory methods. Data were analyzed using t tests and the Pearson correlation.
  
  
  RESULTS
  aPC-SR was below 2 SD for 5 of the cancer patients (13%), but none of the controls; only 1 of the 5 had the factor V Leiden mutation. aPC-SR was inversely correlated (p < 0.01) with factor VIII and fibrinogen in patients and with prothrombin activation fragment 1.2 (F1.2) in controls. Patient factor VIII, von Willebrand factor, (vWF), fibrinogen, F1.2 and D dimer were all significantly increased (p < 0.01; antithrombin III, protein C and proteins were similar to controls. Factor VIII correlated with vWF (p < 0.001) and F1.2 with d-dimer (p < 0.001). Other associations (p < 0.05) were observed between factor V and protein C, fibrinogen and protein C, factor V and antithrombin III and protein C and antithrombin III. Four cancer patients had a history of thromboembolism; their aPC-SR was similar to that of patients without thrombosis. Of the several coagulation measures examined, only vWF was higher in the patients with thrombosis (p = 0.01).
  
  
  CONCLUSIONS
  Cancer patients have evidence of intravascular coagulation and increases in procoagulants and may have aPC resistance. The aPC resistance is not due to factor V Leiden, but is rather associated with elevated levels of factor VIII and fibrinogen, and in itself does not predict thrombosis.
authors.affiliation: Department of Medicine, Northwestrn University Medical School, Chicago, Ill., USA.
authors.forename: D
authors.initials: D
authors.lastname: Green
authors.forename: K
authors.initials: K
authors.lastname: Maliekel
authors.forename: E
authors.initials: E
authors.lastname: Sushko
authors.forename: R
authors.initials: R
authors.lastname: Akhtar
authors.forename: G A
authors.initials: GA
authors.lastname: Soff
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000990:Antithrombin III / Q000032:analysis; D001777:Blood Coagulation; D019008:Drug Resistance, Neoplasm; D005165:Factor V / Q000235:genetics / Q000378:metabolism*; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis; D005340:Fibrinogen / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009369:Neoplasms / Q000097:blood*; D010314:Partial Thromboplastin Time; D016133:Polymerase Chain Reaction; D011486:Protein C / Q000494:pharmacology*; D017293:Protein S / Q000032:analysis; D014841:von Willebrand Factor / Q000032:analysis
chemical_list: D005338:Fibrin Fibrinogen Degradation Products; D011486:Protein C; D017293:Protein S; C095381:factor V Leiden; C036309:fibrin fragment D; D014841:von Willebrand Factor; D000990:Antithrombin III; D005165:Factor V; D005340:Fibrinogen