Background: National and international guidelines for the diagnosis and treatment of cancer associated venous thromboembolism (CAT) recommend anticoagulation treatment for 3 to 6 months and a re-evaluation for resumption depending on the individual risk of every patient. In CAT low molecular weight heparin (LMWH) was estimated to be the most effective and safest treatment option in 2015. However, it remains unclear how cancer patients with VTE were (treated in clinical daily care in Germany. In former register trials, the specific characteristics of individual cancer patients were insufficiently characterized and inadequately discussed. Special aspects of daily care are lacking in most publications. Methods: The GECAT register was set up for Berlin´s two main hospital companies Charité-Universitaetsmedizin Berlin and Vivantes, (both covering about 50 % of the hospital beds in Berlin) to document prospectively patients with a newly diagnosed VTE . Patients with the diagnosis of cancer within 2 years prior to the VTE got basis documentation by a physician after informed consent. A follow up of these patients was scheduled after 3 and 6 months per telephone interview. Points of interest were: kind and location of the VTE event, diagnostic procedures, drug and dosage of initial and follow-up anti-coagulation treatment, relapse of VTE or bleeding complications, serious adverse events, mortality, and date and reason for determination of anticoagulation. Primary objective was to evaluate the treatment reality of patients with cancer associated VTE in clinical daily practice. Results: Between May 2015 and May 2017, 382 patients (pts) with active cancer within the last 2 years and newly diagnosed VTE gave consent to this register trial. 193 (50.5%) were female, median age was 65 years (range 19-89). For 133 pts (34.8%), VTE was the primary reason for admission at hospital, 34.3% were referred by their oncologist, 13,6% by their general practitioner, 15,5% by other treating physicians and 36.6% directly via the emergency department. 182 pts (47.6%) had pulmonary embolism, 268 pts (70.2%) had venous thrombosis and 18,6%71 pts (18.6%) had both. The most common cancer sites were lung (n=57, 14,9%), gynecological (n=44, 11,5%), colorectal (n=40, 10,5%) and pancreatic cancer (n=33 8,6%); 204 pts (56%) with solid tumors presented with stage IV diseases; 60 pts (15.7%) had hematological malignancies. 279 pts (73%) received anticancer treatments at the time of diagnosis of VTE. 148 (38.7%) pts died in the 6 months study period (20 pts died in hospital after admission, 90 pts within the first 3 months and 38 pts within the 6 months follow up). Initially, the majority of pts (n=350; 91.6%) was treated with LMWH. After discharge from hospital 78.7% remained on LMWH and 12.7% were treated with direct oral anticoagulants (DOACs). After 3 months 64.9% of pts received LMWH and 26.1% DOACs; after 6 months 48.4% LMWH and 44% DOACs. Responsible for the anticoagulation treatment decisions was mostly the oncologist (58%), followed by the general practitioner (26.3%) and other physicians (15,7%) . During the initial hospital stay, 2.6% of pts had a bleeding complication and 0.8% were diagnosed with a progress of VTE. At 6 months follow up, 6.4% reported bleeding complications and 2.4% recurrent VTE. Conclusion: The GECAT register trial gives new and clinically relevant information about the clinical daily care practice of cancer patients with newly diagnosed VTE in Berlin, Germany. The treating oncologist is in most cases responsible for the treatment. Disclosures Sinn: LEO: Research Funding; Bayer Healthcare AG: Research Funding; Servier: Honoraria, Research Funding; Astra Zeneca: Honoraria, Research Funding; Amgen: Honoraria; Sanofi: Honoraria. Scholz:Celgene: Consultancy; GILEAD: Consultancy, Speakers Bureau; Roche: Consultancy; Janssen-Cilag: Consultancy; Hexal: Consultancy; Novartis: Consultancy; Pfizer: Speakers Bureau; Takeda: Consultancy; Daiichi Sankio: Consultancy. Klamroth:Bayer, Biomarin, CSL Behring, Novo Nordisk, Octapharma, Pfizer, Roche, SOBI, Takeda: Consultancy; Bayer, Novo Nordisk, SOBI: Research Funding.