The working hypothesis of this study establishes that the risk of cancer patients suffering a thromboembolic event is conditioned by individual genomic factors. The genes to be analyzed have clearly demonstrated their relationship with thromboembolic disease in other clinical contexts. This study is considered the initiation of a field of research in genomic risk markers indicating a risk of thrombosis in cancer patients. The ultimate goal of the study is to establish a clinic-genomic score for selecting patients with a high risk of suffering thrombotic events who can benefit from guided thromboprophylaxis. Its secondary goal is to prevent the adverse effects of ineffective therapies in other patients (low-risk patients not requiring an anti-thrombotic prophylaxis).