In patients who have undergone endoscopic polypectomy, subsequent treatment with low-dose metaformin, a diabetes drug, may reduce the risk of metachronous colorectal adenomas and polyps, according to a new study reported in Lancet Oncology.
Researchers conducted a double-blind, randomized, phase III trial of 151 patients from five sites in Japan. The patients, who previously had single or multiple colorectal adenomas or polyps resected by endoscopy, were randomized to receive 250 mg per day of metformin or placebo.
After one year, follow-up endoscopy was performed. Hyperplastic polyps or adenomas were found in 38% of patients in the metformin group versus 56.5% in the placebo group.
Adverse events occurred in 11% of patients, and all were grade 1. Patients in the metformin group experienced diarrhea, rash, and constipation, and patients in the placebo group had abdominal pain, diarrhea, constipation, and alopecia.
The researchers concluded that using low-dose metformin in patients without diabetes is safe and reduced the prevalence and number of adenomas or polyps after polypectomy. However, they cautioned that additional large, long-term studies are needed to confirm the results.