Impact of Pretreatment With Metformin on Colorectal Cancer Stem Cells (CCSC) and Related Pharmacodynamic Markers

Metformin is drug that is normally used to treat people with diabetes. New research has discovered that metformin may also kill cancer stem cells. These cancer stem cells make up only a small portion of a cancer, but may be responsible for resistance to chemotherapy or for causing recurrence of the cancer. The purpose of this study is to determine the effect of metformin on colorectal cancer tumors. The study is designed to develop the methods to test tumors for cancer stem cells and then to determine the difference between treating with metformin and not treating with metformin with regard to the cancer stem cells. This research is investigational because the effect of metformin on cancer stem cells is not known in humans. Also, in patients who are not diabetic, metformin would normally not be given prior to surgery.