Rivaroxaban vs placebo for extended antithrombotic prophylaxis after laparoscopic surgery for colorectal cancer

The clinical benefit of extended prophylaxis for venous thromboembolism (VTE) after laparoscopic surgery for cancer is unclear. The efficacy and safety of direct oral anticoagulants for this indication are unexplored. PROphylaxis of venous thromboembolism after LAParoscopic Surgery for colorectal cancer Study II (PROLAPS II) was a randomized, double-blind, placebo-controlled, investigator-initiated, superiority study aimed at assessing the efficacy and safety of extended prophylaxis with rivaroxaban after laparoscopic surgery for colorectal cancer. Consecutive patients who had laparoscopic surgery for colorectal cancer were randomized to receive rivaroxaban (10 mg once daily) or a placebo to be started at 7 ± 2 days after surgery and given for the subsequent 3 weeks. All patients received antithrombotic prophylaxis with low-molecular-weight heparin from surgery to randomization. The primary study outcome was the composite of symptomatic objectively confirmed VTE, asymptomatic ultrasonography-detected deep vein thrombosis (DVT), or VTE-related death at 28 ± 2 days after surgery. The primary safety outcome was major bleeding. Patient recruitment was prematurely closed due to study drug expiry after the inclusion of 582 of the 646 planned patients. A primary study outcome event occurred in 11 of 282 patients in the placebo group compared with 3 of 287 in the rivaroxaban group (3.9 vs 1.0%; odds ratio, 0.26; 95% confidence interval [CI], 0.07-0.94; log-rank P = .032). Major bleeding occurred in none of the patients in the placebo group and 2 patients in the rivaroxaban group (incidence rate 0.7%; 95% CI, 0-1.0). Oral rivaroxaban was more effective than placebo for extended prevention of VTE after laparoscopic surgery for colorectal cancer without an increase in major bleeding. This trial was registered at www.clinicaltrials.gov as #NCT03055026.