The first international urokinase/warfarin trial in colorectal cancer. Randomized trial of chemotherapy and radiation therapy with or without warfarin for limited-stage small-cell lung cancer: a Cancer and Leukemia Group B study. Effect of warfarin anticoagulation on survival in carcinoma of the lung, colon, head and neck, and prostate. Final report of VA Cooperative Study #75. Double-blind randomised trial of a very-low-dose warfarin for prevention of thromboembolism in stage IV breast cancer. A randomized trial of anticoagulation with warfarin and of alternating chemotherapy in extensive small-cell lung cancer by the Cancer and Leukemia Group B.
Three hundred and forty-four patients with operable colorectal adenocarcinoma, Dukes' stage B or C, were entered into a randomized controlled trial of intraoperative and postoperative intravenous urokinase and/or long-term sodium warfarin therapy. The factorial design of the trial allowed evaluation of each therapy separately. Age, sex, Dukes' stage and cancer site were similar in the treatment groups. Using life-table methods, survival and recurrence/metastases free survival were estimated up to 6 years postoperatively. No significant effects of either therapy on these endpoints were found. Studies by the Veterans Administration Cooperative Studies Program and Cancer and Leukemia Group B (CALGB) suggested that the addition of warfarin to chemotherapy might enhance response and/or survival in small-cell lung cancer (SCLC). This randomized study evaluated the effect of warfarin with chemotherapy and radiation therapy in limited-stage SCLC.
                Patients were randomized to receive warfarin or no warfarin. All patients received three cycles of doxorubicin, cyclophosphamide, and etoposide (ACE). Cycles 4 and 5 (cisplatin, cyclophosphamide, and etoposide [PCE]) were given concurrently with radiation therapy. Three cycles of ACE were given after chemoradiation therapy, but were discontinued due to a high rate of pulmonary toxicity.
                There were no significant differences in response rates, survival, failure-free survival, disease-free survival, or patterns of relapse between the warfarin-treated and control groups. In patients treated according to the initial design, an increase in failure-free survival seen with warfarin treatment approached significance (P = .07). Preamendment results, while not significant, did not have superimposable treatment survival curves. A landmark analysis at 8 months showed a median survival time after the landmark for complete responders of 33 months with warfarin treatment compared with < or = 13.75 months for complete or partial responders not treated with warfarin (P = .05). Differences between the complete responders in this preamendment population were not significant (P = .103).
                Warfarin does not appear to improve outcome significantly in limited-stage SCLC. However, the differences in some variables between populations before the protocol amendment correspond to the favorable effects of anticoagulants observed in previous studies. VA Cooperative Study #75 was established to test in a controlled, randomized trial the hypothesis that warfarin anticoagulation would favorably affect the course of certain types of malignancy. No differences in survival were observed between warfarin-treated and control groups for advanced non-small cell lung, colorectal, head and neck and prostate cancers. However, warfarin therapy was associated with a significant prolongation in the time to first evidence of disease progression (P = 0.016) and a significant improvement in survival (P = 0.018) for patients with small cell carcinoma of the lung, including the subgroup of patients with disseminated disease at the time of randomization (P = 0.013). A trend toward improved survival with warfarin treatment was observed for the few patients admitted to this study with non-small cell lung cancer who had minimal disease at randomization. These results suggest that warfarin, as a single anticoagulant agent, may favorably modify the course of some, but not all, types of human malignancy, among which is small cell carcinoma of the lung. Further trials of warfarin may be indicated in patients with limited disease who have cell types that failed to respond when advanced disease was present. Patients receiving chemotherapy for metastatic breast cancer are at high risk of thromboembolic disease. Long-term oral anticoagulant therapy is needed but increases the risk of haemorrhagic complications. We have assessed the safety and efficacy of warfarin in very low doses as prophylaxis. Women receiving chemotherapy for metastatic breast cancer were randomly assigned either very-low-dose warfarin (152 patients) or placebo (159). The warfarin dose was 1 mg daily for 6 weeks and was then adjusted to maintain the prothrombin time at an international normalised ratio (INR) of 1.3 to 1.9. Study treatment continued until 1 week after the end of chemotherapy. The average daily dose from initiation of titration was 2.6 (SD 1.2) mg for the warfarin group and the mean INR was 1.52. The mean time at risk of thrombosis was 199 (126) days for warfarin-treated patients and 188 (137) days for placebo recipients (p = 0.45). There were 7 thromboembolic events (6 deep-vein thrombosis, 1 pulmonary embolism) in the placebo group and 1 (pulmonary embolism) in the warfarin group, a relative risk reduction of about 85% (p = 0.031). Major bleeding occurred in 2 placebo recipients and 1 warfarin-treated patient. There was no detectable difference in survival between the treatment groups. Very-low-dose warfarin is a safe and effective method for prevention of thromboembolism in patients with metastatic breast cancer who are receiving chemotherapy. The Cancer and Leukemia Group B (CALGB) conducted a prospective randomized trial to evaluate the role of warfarin and alternating chemotherapy in extensive small-cell lung cancer (SCCL). After stratification for sex and performance status, patients were randomly assigned to receive chemotherapy with methotrexate, doxorubicin (Adriamycin; Adria Laboratories, Columbus, OH), cyclophosphamide, and lomustine (CCNU) (MACC), or MACC plus warfarin (MACC + W), or mitomycin, etoposide, cisplatin, and hexamethylmelamine alternating with MACC (MEPH/MACC). Warfarin was given continuously to maintain a prothrombin time of one and one half to twice the control values. A total of 328 patients were enrolled, and 294 were evaluable. There was a statistically significant advantage in objective response rates (complete [CR] and partial responses [PR], respectively) for MACC + W (17% and 50%) as compared with MACC alone (8% and 43%) or MEPH/MACC (10% and 38%) (P = .012). Both failure-free survival (P = .054 Wilcoxon test) and overall survival (P = .098 Wilcoxon test) were higher on MACC + W (median, 6.6 months and 9.3 months, respectively), as compared with MACC (5.0 months and 7.9 months) and MEPH/MACC (5.0 months and 7.9 months). Toxicity was comparable among the three arms, except for increased hemorrhagic events on MACC + W, which were life-threatening in four patients (4%), and lethal in two others (2%). These data support the role of warfarin in the treatment of SCCL, but do not establish its mechanism of action. Warfarin deserves further studies in SCCL, particularly in patients with limited disease.
Existing evidence does not suggest a mortality benefit from oral anticoagulation in patients with cancer while increasing the risk for bleeding.