The study is classified as an observational pharmacological study, spontaneous, monocentric, and both retrospective and prospective for adult patients with a diagnosis of venous thromboembolism in the context of neoplasia, followed at the SSD Angiology and Coagulation Disorders of the IRCCS Azienda Ospedaliero-Universitaria di Bologna and The Cardiovascular Medicine Department, specifically the Angiology Unit, of the IRCCS Arcispedale S. Maria Nuova in Reggio Emilia, from 01/01/2016 to 30/06/2027. The study, including data analysis, is expected to conclude by 31/12/2027. Patients were treated according to clinical practice, in accordance with the physician's judgment and the information provided in the product's technical datasheet for any concomitant therapies administered as per clinical practice. The primary objective of the study is to evaluate the frequency of thrombotic and hemorrhagic complications during treatment with low molecular weight heparin or direct oral anticoagulants in patients with venous thromboembolism and solid and hematological neoplasms attending outpatient care at the SSD Angiology and Coagulation Disorders of the IRCCS AOUBO and The Cardiovascular Medicine Department, specifically the Angiology Unit, of the IRCCS Arcispedale S. Maria Nuova in Reggio Emilia, following the initiation of anticoagulant therapy (LMWH or DOACs). The secondary objectives of the study are: * To identify risk factors for hemorrhagic complications and bleeding risk during anticoagulant treatment for CAT; * To assess the applicability and reliability of a score, which is not currently in use in clinical practice, without impacting the care process and clinical decisions, in a prospective cohort of patients with CAT.