Summary Objectives: To compare the complication rate (bleeding and thrombosis) of oral anticoagulation in a cohort of patients with cancer to a cohort without cancer Design: Prospective cohort study Setting: Outpatient anticoagulation clinic in a community hospital Patients: Consecutive patients enrolled in an anticoagulation clinic: 44 with cancer, 64 without cancer Interventions: Patients received prophylactic doses of Warfarin (target INR 2–3 in the majority of instances) and complication rates were assessed Measurements: Major bleeding (strictly defined), minor bleeding, recurrent thrombosis, proportion of time with therapeutic INR, frequency of clinic visits Results: The rates of major bleeding, minor bleeding, and recurrent thrombosis were not statistically significantly different in the two groups of patients. Therapeutic INR’s were more difficult to sustain in the cancer patients as compared to the non-cancer patients (43.3% vs 56.9%, p <0.0001). There was a non significant trend towards more frequent monitoring for the cancer patients compared with the noncancer patients (4.6 vs 3.5 visits per treatment month, p = 0.14) Conclusions: Oral anticoagulation is safe and effective in the patient with cancer. It is more difficult to sustain a therapeutic INR in the cancer patients and they may need more frequent monitoring to achieve a low complication rate

The purpose of this study was to establish the safety and efficacy of sodium warfarin in the secondary prophylaxis of venous thrombosis in patients with cancer. This was an inception cohort study of patients enrolled in an anticoagulation clinic between July 1991 and October 1996. The rates of bleeding and recurrent thrombosis were evaluated in all the patients, and the results in patients with cancer (n = 104) were compared with those without cancer (n = 208). The rate of major hemorrhage was 0.4% and 0.3% per treatment month in the patients with cancer and those without cancer, respectively. The rates of recurrent thrombosis were 1.2% and 0.2% per treatment month in the patients with cancer compared with those without cancer, respectively. We conclude that warfarin is safe when used for the secondary prophylaxis of patients with cancer who have had a venous or arterial thrombosis, and the risk of major hemorrhage is not significantly different when compared with the risk in patients without cancer. The rate of recurrent thrombosis is approximately sixfold higher in patients with cancer being treated with warfarin for secondary prophylaxis of thrombosis compared with patients without cancer. Nonetheless, the rate of recurrent thrombosis is not overly excessive, and warfarin can be viewed as a relatively effective form of therapy for these patients.

Patients with cancer had a higher rate of all bleeding episodes, but the analysis for major bleeding included too few patients to conclude that cancer predicted for major bleeding. A large inception cohort shrdy identified cancer or severe anemia as a risk factor for bleeding after the initiation of anticoagulant ttrerapy (12). However many patients were anticoagulated after cardiac surgery 607o) and most patients Q77o) underwent invasive procedures during ttre hospitalization. These results, therefore, may not be directly comparable to patients with cancer who are treated for acute thromboembolism.