Does Metformin Affect The Incidence of Colonic Polyps and Adenomas in Patients with Type 2 Diabetes Mellitus?

Abstract

Background/AimsColorectal cancer (CRC) develops from colonic adenomas. Type 2 diabetes mellitus (DM) is associated with a higher risk of CRC and metformin decreases CRC risk. However, it is not certain if metformin affects the development of colorectal polyps and adenomas. This study aimed to elucidate if metforminaffects the incidence of colonic polyps and adenomas in patients with type 2 DM.MethodsOf 12,186 patients with type 2 DM, 3,775 underwent colonoscopy between May 2001 and March 2013. This study enrolled 3,105 of these patients, and divided them in two groups: 912 patients with metformin use and 2,193 patients without metformin use. Patient clinical characteristics, polyp and adenoma detection rate in the two groups were analyzed retrospectively.ResultsThe Colorectal polyp detection rate was lower in the metformin group than in the non-meformin group (39.4% vs. 62.4%, P<0.01). Colorectal adenoma detection rate was significantly lower in the metformin group than in the non-metformin group (15.2% vs. 20.5%, P<0.01). Fewer advanced adenomas were detected in the metformin group than in the non-metformin group (12.2% vs. 22%, P<0.01). Multivariate analysis identified age, sex, Body mass index and metformin use as factors associated with polyp incidence, whereas only metforminwas independently associated with decreased adenoma incidence (Odd ratio=0.738, 95% CI=0.554-0.983, P=0.03).ConclusionsIn patients with type 2 DM, metformin reduced the incidence of adenomas that may transform into CRC. Therefore, metformin may be useful for the prevention of CRC in patients with type 2 DM.

Metformin, Diabetes, and Survival among U.S. Veterans with Colorectal Cancer

“…These effects are particularly intriguing for CRC because Peutz-Jeghers polyposis involves loss of LKB1, a tumor suppressor that also regulates AMPK. Metformin also appears to inhibit polyp formation and aberrant crypt foci (40–42). …”

Associations between amount of smoking and alcohol intake and risk of colorectal neoplasm

“…In fact, several recent studies have reported that cigarette smoking, obesity, and metabolic syndrome, as well as age and family history of CRC, are risk factors for colorectal neoplasm (CRN). [4][5][6] In particular, many previous studies have shown a consistent association between cigarette smoking and CRN risk. [7][8][9][10][11][12][13] However, most of these studies confirmed smoking as a risk factor for CRN through comparisons of never smokers to current or ex-smokers, and only some studies investigated the risk of CRN in detail according to the amount of smoking.…”

Postoperative adjuvant chemotherapy is associated with a lower incidence of colorectal adenomas in patients with previous colorectal cancer

“…In terms of cancer prevention, previous studies have investigated the preventive effect of aspirin, statins, metformin, and other medications used for other chronic diseases in the development of cancer and precancerous lesions, including colorectal adenoma. [7][8][9][10][11][12] Most patients with cancer are treated with chemotherapy with postoperative adjuvant or palliative aim. However, the effect of this chemotherapy on the precancerous lesions of many cancers is unknown.…”