This is a randomized, double-blinded placebo controlled clinical investigation of the effects of short term oral Metformin therapy on biomarkers for tumor growth in subjects with newly diagnosed colon or rectal adenocarcinoma. Metformin is a well-tolerated drug widely prescribed for treatment of Type 2 diabetes mellitus. Preliminary studies have generated the hypothesis that metformin may have positive effects on both prevention and survival of colon cancer subjects. Clinical trials are ongoing to explore this possibility in breast cancer (NCT01101438). This investigation is the first study of Metformin in colorectal cancer (CRC) patients, and is designed to understand the mechanism of its anti-cancer actions, if any, and its interactions with biomarkers in colorectal cancer patients.~Based upon epidemiological studies, it is hypothesized that there are independent actions of Metformin on the outcome of subjects with CRC. Also hypothesized is that metformin effects on CRC cell growth will correlate with this drug's effects on markers mentioned above, because the markers are closely related to tumor growth and metastases.
The purpose of this study is to investigate the effects of short term oral Metformin therapy on biomarkers for tumor growth in subjects with newly diagnosed colon or rectal adenocarcinoma.~It is hypothesized that there are independent actions of Metformin on the outcome of subjects with colorectal cancer (CRC). Also hypothesized is that metformin effects on CRC cell growth will correlate with this drug's effects on markers mentioned above, because the markers are closely related to tumor growth and metastases.