The prevalence of thrombocytopenia in patients with acute cancer-associated thrombosis

Venous thromboembolism (VTE) and thrombocytopenia are frequently encountered complications in patients with cancer. Although there are several studies evaluating the safety and efficacy of anticoagulation regimens in patients with cancer-associated thrombosis (CAT) with thrombocytopenia, there is a paucity of data assessing the scope of the concurrent diagnoses. This study evaluates the prevalence of thrombocytopenia among patients with acute CAT. A retrospective cohort analysis of adult patients with cancer was conducted at Beth Israel Deaconess Medical Center between 2010 and 2021 with CAT (acute VTE within 6 months after new diagnosis of malignancy). VTE included acute deep vein thrombosis, pulmonary embolism, abdominal or intrathoracic venous thrombosis, and cerebral sinus thrombosis. The lowest platelet count within 2 weeks of (before or after) the index VTE event was identified to assess the frequency and grade of concurrent thrombocytopenia. We identified 3635 patients with CAT (80% solid tumors, 18% hematologic malignancies, and 2% multiple concurrent cancer diagnoses). Thrombocytopenia (defined as platelet count <100 000/μL) occurred in 22% (95% CI 21%-24%) of patients with CAT with solid tumors diagnoses and 47% (95% CI 43%-51%) of patients with CAT and hematologic malignancies. Severe thrombocytopenia (platelet count <50 000/μL) occurred in 7% (95% CI 6%-8%) of patients with solid tumors and 30% (95% CI 27%-34%) of patients with hematologic malignancies. Concurrent diagnoses of CAT and thrombocytopenia are very common, especially among patients with hematologic malignancies.