Influence of primary cancer site on clinical outcomes of anticoagulation for associated venous thromboembolism

Introduction: The outcome of anticoagulation for cancer-associated venous thromboembolism (Ca-VTE) differs according to cancer location, but data are limited and inconsistent. Materials and methods: Patients with acute venous thromboembolism (VTE) enrolled between 03/01/2013 and 04/30/2021 were followed prospectively to assess VTE recurrence, major bleeding (MB), clinically relevant non-major bleeding (CRNMB), and death. Results: There were 1702 (45.3 %) patients with Ca-VTE including: gastrointestinal (n = 340), pancreatic (n = 223), hematologic (n = 188), genitourinary (n = 163), lung (n = 139), ovarian (n = 109), breast (n = 97), renal (n = 75), prostate (n = 73), hepatobiliary (n = 70), brain (n = 57), and other cancers (n = 168); 2057 VTE patients had no cancer (NoCa-VTE). Hepatobiliary cancer had the highest VTE recurrence (all rates 100 person-years) of all cancers and higher compared to NoCa-VTE (13.69, p = 0.01), while the MB rate, although numerically higher (15.91), was not different (p = 0.09). Another 3 cancers had higher VTE recurrence but similar MB rates compared to NoCa-VTE: genitourinary [(9.59, p = 0.01) and (7.03, p = 1.0)], pancreatic [(9.74, p < 0.001) and (5.47, p = 1.00)], and hematologic [(5.29, p = 0.05) and (3.59, p = 1.0)]. Renal cancer had the highest rate of MB among all cancers and was higher than that of NoCa-VTE (16.49; p < 0.001), with no difference in VTE recurrence (1.62; p = 1.0). VTE recurrence and MB rates were not significantly different between NoCa-VTE and gastrointestinal, lung, breast, prostate, and brain cancers. CRNMB rates were similar and mortality higher in Ca-VTE patients, except for prostate and breast cancer, compared to NoCa-VTE. Conclusions: Significant differences in clinical outcomes indicate that anticoagulation strategies may need to be tailored to the primary cancer location.