Thromboprophylaxis in active cancer patients: Is it a controversial clinical issue or not? Preliminary results of ACT4CAT study

e18803 Background: Cancer Associated Thrombosis (CAT) is an increasing challenge for oncology patients since oncologists sometimes are reluctant to mitigate the risk with thromboprophylaxis. Active cancer patients while receiving chemotherapy have a 7fold risk of thrombosis compared with no cancer patients. Anticoagulation holds a prominent place in prevention of CAT usually with Low Molecular Weight Heparins (LMWHs). Methods: ACT4CAT is prospective observational study conducted by HeSMO across Greece, aiming to record the clinical practice of CAT prophylaxis in patients with solid tumors. Ambulatory, high thrombotic risk, active cancer patients who received thromboprophylaxis enrolled after signing informed consent. Results: Preliminary results collected from 18 oncology departments. From 431 enrolled patients 322 (65.4%) had completed the study. Tumor types included: lung 28.8%, gastrointestinal 39.8%, gynecological 7.0%, breast 4.4%, urological 7.0% and others 20%. Majority of patients (88.2%) received High-Risk for Thrombosis Chemotherapy Agents (HRTCAs) such as platinum agents (55.9%), antimetabolites (44.7%) and immunotherapy (12.6%). In 1st line were 62.1%, 2nd line 18.4%, adjuvant 8.9% and neoadjuvant 2.4%. The following table depicts: age, gender, metastatic disease, Khorana score ≥2 and HRTCAs. All patients received thromboprophylaxis for 5.3±3.6 months with: tinzaparin 90.8%, fondaparinux 5.5%, bemiparin 1.5%, enoxaparin 1.2%, apixaban 0.5% and rivaroxaban 0.5%. Intermediate doses received 70.9% of patients regardless clinical setting (1st, 2nd, adjuvant & neoadjuvant: 70.2%, 79.2%, 51.3% and 70.0% respectively, p = 0.0254), although intermediate doses were used more in metastatic stages (OR:2.4 95%CI: 1.4-4.2, p = 0.0028). Nine thrombotic events reported (2.1%, 95%CI: 1.1-3.9%), irrespective of clinical setting but with a trend towards prophylactic doses. Eleven grade 1 bleedings reported (2.6%, 95%CI: 1.4-4.5%), despite clinical setting or dose used. Conclusions: Thromboprophylaxis in ambulatory active cancer patients with high thrombotic risk is safe and effective. Oncologists are alerted about CAT negative influences in cancer patients’ prognosis. Apart from Khorana score, factors such as metastases, use of HRTCAs and drug-drug interactions influence the clinical decision of thromboprophylaxis in active cancer patients mainly with LMWHs and quite often with intermediate doses regardless clinical setting. Clinical trial information: NCT03909399. [Table: see text]