Incidence of Venothromboembolism (VTE) in Patients (pts) with Acute Lymphocytic Leukemia (ALL), Burkitt’s Leukemia/Lymphoma (BL) or Lymphoblastic Leukemia (LL).

Background: Pts with cancer are at increased risk of thromboembolic events with potentially life-threatening consequences. The incidence of VTE in cancer pts has been estimated at 1 in 250. Although most of these episodes are associated with solid tumors, VTE is also observed in pts with acute leukemias, even in the presence of thrombocytopenia. Anticoagulation in this pt population can be particularly problematic if pts are undergoing myelosuppressive chemotherapy. VTE prophylaxis is often not given because of the perceived high risk of bleeding with a presumed low risk of VTE.

Method: As little is known about the incidence and significance of VTE in pts with acute leukemia, we conducted a retrospective chart review of 223 pts with ALL, BL, or LL who received a hyper-CVAD regimen (fractionated cyclophosphamide, vincristine, doxorubicin, dexamethasone alternating with methotrexate and cytarabine) with or without rituximab, maintenance chemotherapy (with L-asparaginase only months #7 & 18), allogeneic stem cell transplant (SCT), or salvage chemotherapy at our institution from November 1999 to May 2005. The median observation period was 112 weeks (range 1–328).

Results: The median age was 51 yrs (range 19–75). 70% were ALL, (50% were Philadelphia positive ALL), 20% Burkitt’s or Burkitt’s-like, and 10% LL. Thirty nine of 223 pts (18%) had confirmed VTE by imaging studies: 12.5% prior to or at the time of diagnosis, 57.5% during consolidation chemotherapy, and 27.5% during maintenance chemotherapy, SCT, or supportive care. Location of VTE varied by site: 3/39 (8%) pulmonary embolus, 16/39 (41%) lower extremity, 2/39 (5%) central venous catheter (CVC), and 18/39 (46%) upper extremity. Two of the 18 with upper extremity VTEs did not have CVC, and an additional 2 had bilateral upper extremity thromboses. The platelet counts were reviewed near the time of VTE diagnosis: 22/39 (56%) had greater than 100 × 10⁹/L, 17/39 (44%) were less than that value, with 76% below 50,000 × 10⁹/L.

Conclusion: Pts with ALL, BL, and LL undergoing therapy are at risk for developing VTE. Thrombocytopenia does not preclude development of VTE. A more detailed analysis will be forthcoming regarding the risk factors for VTE in this pt population, the current medical practices and bleeding complications with VTE prophylaxis and treatment, and the effect on therapy administration and overall survival. Practice guidelines for management of acute leukemia pts with thromboembolic events should be pursued.