Introduction:The case fatality rate (CFR) of recurrent venous thromboembolism (VTE) and clinically relevant bleeding (CRB) are useful to evaluate the risk and the benefits of anticoagulant therapy. We analyze the CFR of recurrent VTE and CRB during anticoagulation in cancer patients with thrombosis.

Methods: Retrospective cohort of consecutive patients with cancer associated thrombosis (CAT). CFR was defined as proportion of total events (recurrent VTE o CRB) resulting in death within the first 10 days after the complication. The proportions were expressed with the 95% confidence interval (95%CI).

Results: From Dec/2007 to Nov/2022, 1095 patients with CAT were included, of which 127 (11.3%) had a recurrent VTE, 143 (11.6%) a CRB and 33 (3%) both. The median follow-up time was 21.7 months (p25-p75: 7.5-40.2). During the initial 3 months of treatment, the CFR of recurrent VTE was 7.4% (IC95% 1-24.5), compared with 5.7% (IC95% 2.4-12.1) beyond this period. The CFR of CRB was 19.1% (95%CI, 9.7-33.6) during the first 3 months and 15.8% (95%CI 9.9-24.3) beyond 3 months. When comparing patients with or without CRB, we observed that patients with CRB were older (66.7±11.9 vs. 63.6±13.2 years; p<0.05) and presented more incidental thrombosis (55.9% vs. 46.5%; p=0.03). The locations of cancer associated with CRB were renal (7% vs. 4%; p<0.05), bladder (8.4% vs. 4.2%; p<0.05) and prostate (11.2% vs. 4%; p<0.05). There were no differences in patients with or without VTE recurrent.

Conclusion: In CAT, the CRF of CRB is higher than the rate of recurrent VTE. The CRF of CRB decreased over time while the rate of recurrent VTE remained stable.