title: PO-32 - Patient, tumour and operative factors influencing perioperative hypercoagulability in colorectal cancer.
abstract: BACKGROUND
  Up to 6% of patients develop venous thromboembolism (VTE) following elective colorectal cancer surgery despite thromboprophylaxis. Clinical practices for perioperative thromboprophylaxis remains variable, particularly the use and duration of extended thromboprophylaxis. Identification of factors associated with a prolonged postoperative hypercoagulable state may allow the development of algorithms that allow more targeted thromboprophylaxis.
  
  
  OBJECTIVE
  To identify patient, tumour and surgical risk factors for prolonged (two and six weeks) hypercoagulability in colorectal cancer patients undergoing surgical resection.
  
  
  METHODS
  In a prospective cohort study (Cancer-induced Hypercoagulability As a Marker of Prognosis [CHAMPion]), plasma d-dimer was measured at 2 and 6weeks post-operatively in patients undergoing elective, curative resection for colorectal cancer. Hypercoagulability (raised D-dimer) at 2 and 6weeks was correlated with patient, tumour and operative factors.
  
  
  RESULTS
  Of the 62 patients recruited (median age 69years [range 39-90]), 37 were male. D-dimer was increased in females compared to males at six weeks (geometric mean (GM) 1,287ng/ml [95% CI 944 - 1,755 vs. 821ng/ml (95% CI 633 - 1064) p=0.03]. Age, smoking, hypertension, use of antiplatelet medication, BMI and WHO performance status were not associated with a prolonged hypercoagulable state. There were no tumour factors (including size/T stage/lymph node involvement/differentiation) associated with a prolonged hypercoagulable state. D-dimer was increased in patients undergoing open surgery (n=39) compared to laparoscopic surgery (n=23) at 2weeks (GM 2,337ng/ml [95% CI 1,806-3,023] vs. 1,212ng/ml [95% CI 898-1,629], p=0.001) and 6weeks (GM 1,162ng/ml [95% CI 818-1647] vs. 723ng/ml [95% CI 533-982]p=0.04). Operative time was not associated with prolonged hypercoagulability. D-dimer had a trend to be increased at 2weeks in patients receiving perioperative blood transfusions (n=8) compared to those that did not (n=54) (GM 2,618ng/ml [95% CI 1,525-4,536] vs. 1613ng/ml [95% CI 1,236 - 2,100] p=0.08).
  
  
  CONCLUSIONS
  Even in this relatively small cohort of patients female gender, open surgery and receiving a blood transfusion are associated with on-going hypercoagulability up to six weeks post operation. This may represent a group where thromboprophylaxis should be targeted.
authors.affiliation: Institute of Cancer Sciences, University of Manchester; Department of Academic Surgery, University Hospital of South Manchester, United Kingdom.
authors.forename: H W
authors.initials: HW
authors.lastname: Clouston
authors.affiliation: Institute of Cancer Sciences, University of Manchester; Department of Academic Surgery, University Hospital of South Manchester, United Kingdom.
authors.forename: P A
authors.initials: PA
authors.lastname: Rees
authors.affiliation: Institute of Cancer Sciences, University of Manchester; Department of Academic Surgery, University Hospital of South Manchester, United Kingdom.
authors.forename: H
authors.initials: H
authors.lastname: Shaker
authors.affiliation: Department of Academic Surgery, University Hospital of South Manchester, United Kingdom.
authors.forename: S
authors.initials: S
authors.lastname: Duff
authors.affiliation: Institute of Cancer Sciences, University of Manchester; Department of Academic Surgery, University Hospital of South Manchester, United Kingdom.
authors.forename: C C
authors.initials: CC
authors.lastname: Kirwan