Long-term outcomes of cancer-related isolated distal deep vein thrombosis: the OPTIMEV study

Background: Isolated distal deep vein thrombosis (iDDVT) (infra-popliteal DVT without pulmonary embolism [PE]) is a frequent event and, in the absence of cancer, is usually considered to be a minor form of venous thromboembolism (VTE). However, the clinical significance of cancer-related iDDVT is unknown. Methods: Using data from the observational, prospective multicenter OPTIMEV cohort, we compared, at 3 years, the incidences of death, VTE recurrence and major bleeding in patients with cancer-related iDDVT with those in cancer patients with isolated proximal DVT (matched 1: 1 on age and sex) and patients with iDDVT without cancer (matched 1: 2 on age and sex). Results: As compared with patients with cancer-related isolated proximal DVT (n = 92), those with cancer-related iDDVT (n = 92) had a similar risk of death (40.8% per patient-year (PY) vs. 38.3% per PY; aHR = 1.0, 95% CI[0.7-1.4]) and of major bleeding (3.8% per PY vs. 3.6% per PY, aCHR = 0.9 [0.3-3.2]) and a higher risk of VTE recurrence (5.4% per PY vs. 11.5% per PY; aCHR = 1.8 [0.7-4.5]). As compared with patients with iDDVT without cancer (n = 184), those with cancer-related iDDVT had a nine times higher risk of death (3.5% per PY vs. 38.3% per PY; aHR = 9.3 [5.5-15.9]), a higher risk of major bleeding (1.8% per PY vs. 3.6% per PY; aCHR = 2.0 [0.6-6.1]) and a higher risk of VTE recurrence (5.0% per PY vs. 11.5% per PY; aCHR = 2.0 [1.0-3.7]). The results remained similar in the subgroup of patients without history of VTE. Conclusion: Patients with cancer-related iDDVT seem to have a prognosis that is similar to that of patients with cancer-related isolated proximal DVT and a dramatically poorer prognosis than patients with iDDVT without cancer. This underlines the high clinical significance of cancer-related iDDVT and the need for additional studies.