Improving Disease-Free Survival in Colorectal Cancer

The human body has a natural stress response to surgery, including the formation of blood clots. This response to surgery has been shown to increase metastases (the spread of cancer cells to other organs in the body). These metastases cannot be seen at the time of surgery but when they grow into new tumors, the cancer has recurred (come back). A blood thinner called "low molecular weight heparin" (LMWH) can suppress the development of metastases after surgery in animal experiments. The investigators want to see if giving patients with colorectal cancer the blood thinner, LMWH, around the time of surgery can decrease the chance of their cancer spreading to other organs (metastases) and coming back (recurrence). The investigators need 1075 patients to answer our scientific question. Patients who give informed consent will be randomly put into one of two groups, the experimental group and the control group. The patients in the control group will be treated with LMWH starting a few hours after surgery and every day until they leave the hospital. This is how most patients are treated after colon cancer surgery (standard care). The patients in the experimental group will be treated with LMWH for a longer period of time, starting on the day they agree to have surgery and continuing for two months after surgery. All the patients will be followed for at least three years after surgery to find out if their cancer has recurred (come back). If LMWH treatment around the time of surgery reduces the chance of recurrence in patients with colorectal cancer, it would improve the health and quality of life for these patients.