Predicting thrombotic risk in patients with classical Hodgkin lymphoma: Thro-HL multicenter study.

Thrombosis Lymphoma (ThroLy) and Khorana scores have been conceived to predict the thrombotic risk in oncohematologic patients. Currently, there is no univocal indication to perform thromboprophylaxis in classical Hodgkin lymphoma (cHL). We performed a retrospective study to validate scores and risk factors in a cohort of consecutive patients with cHL, treated from 2014 to 2022 outside clinical trials. A total of 470 cHL patients without thromboprophylaxis were included, of whom 57 (12%) experienced a thrombotic event (TE) at 3.3 months (range 1-52) from diagnosis. Neither Khorana nor ThroLy score significantly predicted the thrombotic risk. In a multivariate analysis including Throly parameters and other risk factors, an independent prognostic impact on the TE risk was found for bulky disease (3 points), ECOG PS 2-4 (2 points), presence of peripherally implanted central venous catheter (2 points), mediastinal involvement (1 point), which were combined in a new risk model (Thro-HL). Low-risk (score 0-1; 39%,  = 183), intermediate-risk (score 2-3; 46%,  = 214), and high-risk (score > 3; 15%,  = 72) patients had a significantly different TE rate, of 2.7%, 16%, and 25% (P < 0.001), respectively. Three-year-thrombotic event-free survival was 97% (CI 95-100) for low-risk and 76% (CI 66-86) for high-risk patients (P < 0.0001, Harrel's -index = 0.70). Thro-HL could be a promising tool to be validated in larger series.