A Study of Initiation Timing of VTE Prevention After Colorectal Cancer Surgery

This study is examining the best timing for starting blood clot prevention (anticoagulation) after surgery for colorectal cancer (cancer of the colon or rectum). Blood clots are a serious risk after major surgery, but starting anticoagulation too soon can increase bleeding risk. **You may be eligible if...** - You are older than 18 - You have been diagnosed with colorectal cancer and are scheduled for surgery (either laparoscopic or open) to remove it - Your surgery is expected to take more than 45 minutes and your expected survival after surgery is more than 6 months - You or your legal guardian can give written consent **You may NOT be eligible if...** - You have significantly impaired kidney or liver function - Your cancer is too advanced or cannot be fully removed - You have a known allergy to blood thinners (low molecular weight heparin) - You have a bleeding disorder, active ulcer, uncontrolled high blood pressure, or recent stroke or brain surgery - You had a blood clot in the past 3 months - You are currently on blood-thinning medications - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.