Reliability and Validity of D-dimer Monitoring for Pulmonary Thromboembolism in Patients with Unresectable, Advanced or Recurrent Colorectal Cancer Treated with Bevacizumab.

Pulmonary thromboembolism (PTE) is one of the leading causes of death among cancer outpatients. The aim of the present study was to investigate the reliability and validity of D-dimer monitoring for PTE in patients with unresectable, advanced or recurrent colorectal cancer treated with bevacizumab. A total of 25 patients with advanced colorectal cancer who received bevacizumab combination chemotherapy as primary treatment were retrospectively reviewed. The selection criteria included that D-dimer tests were performed repetitively, and that chest and abdominal contrast-enhanced CT scans were completed. The D-dimer levels and the presence or absence of PTE on CT images were retrospectively examined. Four cases (16%) were detected as having asymptomatic PTE. The D-dimer values at the onset of PTE were 14.2, 4.6, 1.1 and 0.9 mu g/ml. The negative predictive value was 90.5% when 3.0 mu g/ml was set as the D-dimer level cutoff value. The incidence of PTE, including asymptomatic PTE, in the present study was higher compared with that reported in previous studies on various types of cancer, of various stages and treated with different chemotherapy regimens. In patients with bevacizumab-treated unresectable, advanced or recurrent colorectal cancer, the D-dimer test was found to be less useful for exclusion diagnosis; however, along with chest CT, it may be useful in the detection and diagnosis of PTE. However, the determination of the optimal reference values and appropriate measurement timing of D-dimer testing requires further study.