T1150 Role of Cyclooxygenase-2 in Cancer Stem Cell Biology and Effect of COX-2 Inhibitors in Anti-Cancer Therapy Targeting Cancer Stem Cells

Background and aims: Clopidogrel and aspirin (ASA) are wildly used in the prevention of cardiovascular and embolic events. However, these combined medications cause significant risk of peptic ulcers and bleeding complications. This case-control study was designed to evaluate the risk of upper gastrointestinal bleeding (UGIB) in clopidogrel and aspirin users who continue receiving standard dose of proton pump inhibitors (PPI). . Methods: Data for clinical information and endoscopic findings were collected during January 2009 and November 2009 from patients who used clopidogrel and/or ASA and continue receiving standard dose of PPI. Patients with history of prior UGIB or abdominal surgery were excluded. Clopidogrel or ASA user was defined as consumption of clopidogrel or ASA for at least 7 days period preceding the episode of bleeding. The UGIB was defined as overt bleeding (hematemesis, positive nasogastric aspirate, and melena) or fall in baseline hematocrit ≥ 5 points within 24 hours of admission. Ulcer was defined at endoscope by breaking mucosa > 3mm in diameter. Results:A total of 175 patients (82 men and 93 women, mean age of 65.3 years) were evaluated in this study including 54 patients (30.9%) with UGIB and 121 patients (69.1%) with dyspeptic symptoms. Male were significantly more common than female patients in bleeding group (61.1 % vs 38.9%: P=0.01). However, the underlying diseases of the patients including cardiovascular diseases, rheumatological diseases and diabetes mellitus were not different between these 2 groups. UGIB was significantly higher in current ASA (325mg) plus clopidogrel user than non-user (16.7% vs 5.8%; P=0.02). The multivariable model suggested that the probability of UGIB event increased with current ASA (325mg) plus clopidogrel use (OR= 2.3, 95%CI =1.2-3.9) in the patients receiving concomitant PPI. Summary: Risk of UGIB events still occur in ASA and clopidogrel users in spite of receiving concomitant PPI. Lower dose of ASA, concomitant higher dose PPI and carefully monitoring of UGIB should be considered in combined ASA and clopidogrel user patients.