A randomized study on 1-week versus 4-week prophylaxis for venous thromboembolism after laparoscopic surgery for colorectal cancer.

OBJECTIVE: To compare the efficacy and safety of antithrombotic prophylaxis given for 1 week or 4 weeks in patients undergoing laparoscopic surgery for colorectal cancer. BACKGROUND: Extending antithrombotic prophylaxis beyond 1 week reduces the incidence of venous thromboembolism (VTE) after open abdominal surgery for cancer. METHODS: In consecutive patients who underwent laparoscopic surgery for colorectal cancer, complete compression ultrasonography of the lower limbs was performed after 8 ± 2 days of antithrombotic prophylaxis. Patients with no evidence of VTE were randomized to short (heparin withdrawal) or to extended (heparin continued for 3 additional weeks) prophylaxis. Complete compression ultrasonography was repeated at day 28 ± 2 after surgery by investigators blinded to treatment allocation. The primary outcome of the study was the composite of symptomatic and ultrasonography-detected VTE at day 28 ± 2 after surgery. RESULTS: Overall, 301 patients were evaluated for inclusion in the study and 225 were randomized. VTE occurred in 11 of 113 patients randomized to short (9.7%) and in none of the 112 patients randomized to extended heparin prophylaxis (P = 0.001). The incidence of VTE at 3 months was 9.7% and 0.9% in patients randomized to short or to extended heparin prophylaxis, respectively (relative risk reduction: 91%, 95% confidence interval: 30%-99%; P = 0.005). The rate of bleeding was similar in the 2 treatment groups. Two patients died during the study period, 1 in each treatment group. CONCLUSIONS: After laparoscopic surgery for colorectal cancer, extended antithrombotic prophylaxis is safe and reduces the risk for VTE as compared with 1-week prophylaxis (NCT01589146).