PO37 | CLINICAL SIGNIFICANCE OF SYMPTOMATIC AND INCIDENTAL VENOUS THROMBOEMBOLISM IN CANCER PATIENTS TREATED WITH APIXABAN

P. Hussaini¹, T.L. Larsen², W. Ghanima^1|3, A.E.A. Dahm^1|2 | ¹Institute of Clinical Medicine, University of Oslo, Oslo, Norway; ²Department of Hematology, Akershus University Hospital; Lørenskog, Norway; ³Clinic of Internal Medicine, Østfold Hospital, Grålum, Norway

Background. Clinical characteristics and outcomes of cancer patients with symptomatic versus incidental venous thromboembolism (VTE) remain poorly described. This study aimed to compare clinical characteristics and outcomes in cancer patients with symptomatic versus incidental venous thromboembolism treated with apixaban.

Methods. In this post-hoc analysis of the CAP study, we explored cancer patients with VTE who received 5 mg apixaban twice daily for 6 months, followed by 2.5 mg apixaban 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 during a 36-month follow-up were compared between symptomatic and incidental VTE.

Results. Of 284 patients, 163 (57%) had incidentally detected VTE. Compared with symptomatic patients, those with incidental VTE had lower BMI, more metastatic disease (79% vs 57%), and more pulmonary and abdominal VTE. Deep vein thrombosis of the leg was higher in the symptomatic group (45.4% vs. 7.4%, p < 0.001). There was more colorectal cancer in the incidental group (31.9% vs. 19.0%, p=0.01) and more hematological (14.1% vs. 5.5%, p=0.01) and breast cancers (14.9% vs. 5.5%, p=0.01) in the symptomatic group. Recurrent VTE occurred in 9.8% of incidental and 6.6% of symptomatic cases (odds ratio (OR) 1.5, 95% confidence interval (CI) 0.6–3.7). Clinically relevant bleeding was more frequent in incidental VTE (26.4% vs. 14.9%; OR 2.1, 95% CI 1.1–3.8) (Figure 1). In a multivariable analysis incidental VTE was associated with bleeding independently of other known risk factors for bleeding, such as higher age and low hemoglobin at baseline.

Conclusions. Incidental and symptomatic VTE in cancer patients have different clinical characteristics. While VTE recurrence was similar, incidental VTE was associated with a higher risk of bleeding during apixaban therapy.