Abstract Body (Do not enter title and authors here): Hypothesis and Purpose: Currently, many cancer patients live longer, and complications during the course of cancer treatment have become important in Cardio-Oncology. Through computed tomography scans for the evaluation of cancer, low-risk pulmonary embolism (PE) among cancer patients, including minor and incidental PE, has become quite common in daily clinical practice. The mainstay of treatment for PE is anticoagulation therapy, while optimal anticoagulation strategies for low-risk PE are not currently established. Current guidelines for venous thromboembolism (VTE) weakly recommend that cancer patients with low-risk PE receive prolonged anticoagulation therapy. However, there has been no randomized clinical trial (RCT) in the issue, including the optimal duration of anticoagulation therapy.
Study Design and Methods: The ONCO PE trial (NCT03895502) is a multicenter, investigator-initiated, open-label, adjudicator-blinded RCT that compared 18-month rivaroxaban treatment and 6-month rivaroxaban treatment in cancer patients with PE of the simplified version of the Pulmonary Embolism Severity Index (sPESI) score=1.
Sample Size: 179
Population Studied: Cancer patients with low-risk PE
Intervention: 18-month rivaroxaban treatment vs. 6-month rivaroxaban treatment
Power Calculations: We calculated the sample size based on previous studies with a power of 80% and 2-sided alpha of 0.05, and we had decided to enroll 330 patients.
Primary End Point: Recurrent VTE at 18 months.
Secondary End Point: ISTH major bleeding at 18 months
Outcome: The trial had prematurely terminated after enrolling a total of 179 patients between February 2021 and March 2023 from 32 centers in Japan. After the exclusion of 1 patient who withdrew consent, the final analytic population consisted of 178 patients. The primary endpoint of recurrent VTE occurred in 5 of the 89 patients (5.6%) in the 18-month rivaroxaban group and in 17 of the 89 (19.1%) in the 6-month rivaroxaban group (odds ratio, 0.25; 95% CI, 0.09-0.72; P=0.01). Among 22 recurrent VTE events, 5 patients presented with a symptomatic recurrent VTE, and recurrent PE occurred in 11 patients including 2 main and 4 lobar PEs, and recurrent DVT in 11 patients including 3 proximal DVTs. The major secondary endpoint of major bleeding occurred in 7 of the 89 patients (7.8%) in the 18-month rivaroxaban group and in 5 of the 89 patients (5.6%) in the 6-month rivaroxaban group (odds ratio, 1.43; 95% CI, 0.44-4.70; P=0.55).