Rationale, design and methodology of TESEO study: a registry of thrombosis and neoplasia of SEOM (Spanish Society of Medical Oncology).

Background And Rationale: Thromboembolic complications are a serious, preventable and common event in cancer patients that contributes to increasing morbidity and mortality. Despite increasing knowledge on cancer-associated thrombosis (CAT), there are still several aspects of diagnosis, clinical management, treatment and prognosis with uncertainties that are under-represented in randomized clinical trials. For this reason, the Spanish Society of Medical Oncology (SEOM) launched in June 2018 a registry of CAT.

Methods/design: TESEO is an ongoing prospective, non-interventional, multicentric study in consecutive cancer patients with newly diagnosed of thromboembolic event (TEE). Eligibility criteria include being  > 18 years with a histologically confirmed diagnosis of cancer and a symptomatic or incidental TEE confirmed with an imaging technique in the previous month or any time after the cancer diagnosis and signing of informed consent. The study consists of two types of integrated but independent prospective registries. Regular CAT sub-registry includes information on patient's cancer´s characteristics, anticoagulant treatment provided and outcome data. Special CAT sub-registry includes variables related to special situations of CAT that comprise patients with severe kidney failure, thrombocytopenia, high risk of bleeding related to the cancer or with coexistence of bleeding and patients who receive new treatments such a targeted therapy, antiangiogenics agents and immunotherapy. The registry considers the status of the cancer and the time to assess how the prognosis is changed based on when the thrombus occurs. Some outcomes such as rethrombosis, major bleeding, tumor progression and survival will be valued in various time intervals including 1, 3, 6 and 12 months after the even in the first year; and then every 6 months until the patient's death.

Results: After 18 months and with 35 centers and researchers, the registry has 1128 patients.

Conclusion: TESEO registry will provide clinical real-world evidence for prevention, treatment and complications of CAT in different scenarios that are under-represented in randomized clinical trials.