Clinical significance of symptomatic and incidental venous thromboembolism in patients with cancer treated with apixaban

Background: Clinical characteristics and outcomes of patients with cancer with symptomatic vs incidental venous thromboembolism (VTE) remain poorly described. Methods: In this post hoc analysis of the apixaban as treatment of venous thrombosis in patients with cancer (CAP) study, we explored patients with cancer with VTE who received apixaban 5 mg twice daily for 6 months and then 2.5 mg twice daily for 30 months. Patients were classified as having symptomatic or incidental VTE at inclusion. The main outcomes were recurrent VTE and clinically relevant bleeding. Baseline characteristics and outcomes were compared between the 2 groups during a 36-month follow-up. Results: Of 284 patients, 163 (57%) had incidentally detected VTE. Compared with symptomatic patients, incidental patients had lower body mass index, more metastatic disease (79% vs 57%), and more pulmonary embolism or abdominal vein thrombosis. Deep vein thrombosis of the leg was more frequent in the symptomatic group (45.4% vs 7.4%, P < .001). There were more colorectal cancers in the incidental group (31.9% vs 19.0%, P = .01) and more hematological (14.1% vs 5.5%, P = .01) or breast cancers (14.9% vs 5.5%, P = .01) in the symptomatic group. Recurrent VTE occurred in 9.8% of incidental and 6.6% of symptomatic patients (subdistribution hazard ratio, 1.5; 95% CI, 0.6-3.5). Clinically relevant bleeding was more frequent in the incidental group (24.5% vs 13.2%; subdistribution hazard ratio, 1.9; 95% CI, 1.1-3.4). In the multivariable analysis, low hemoglobin and incidental VTE were independently associated with bleeding. Conclusion: The characteristics and outcomes in patients with incidental VTE differed from those with symptomatic VTE. While VTE recurrence was similar between the two groups, incidental VTE was associated with a higher risk of bleeding.