Published online Apr 14, 2021. doi: 10.3748/wjg.v27.i14.1362
Peer-review started: December 24, 2020
First decision: February 11, 2021
Revised: February 14, 2021
Accepted: March 17, 2021
Article in press: March 17, 2021
Published online: April 14, 2021
Colorectal cancer (CRC) is among the most prevalent cancers worldwide, and its prevention and reduction of incidence is imperative. The presence of diabetes has been associated with a 30% increased risk of CRC, likely through the mechanism of hyperinsulinemia, which promotes tumorigenesis via the insulin receptor in the epithelium or by insulin-like growth factor pathways, inflammation, or adipokines, inducing cancer cell proliferation and cancer spread. Metformin, the first-line agent in treating type 2 diabetes, has a chemopreventive role in CRC development. Additionally, preclinical studies suggest synergistic effects of metformin with oxaliplatin in inhibiting in vitro models of colon cancer. Although preclinical studies on the post diagnostic use of metformin were promising and suggested its synergistic effects with chemotherapy, the data on the possible effects of metformin after surgery and other CRC treatment in the clinical setting are less conclusive, and randomized controlled trials are still lacking.
Core Tip: Metformin is one of the oldest oral antidiabetic agents used to treat type 2 diabetes mellitus. While there is substantial evidence that metformin may have a chemopreventive role in colorectal cancer (CRC) development, the data on the possible effects of metformin after surgery and other CRC treatment is much less conclusive.