Intervention: Metformin Hydrochloride
Trial phase: Phase 2
SMILES: CN(C)C(=N)N=C(N)N.Cl
Sex: All
Age groups: Adult | Older Adult
Healthy volunteers: No
Participants at risk: 45
Group description: Patients receive metformin hydrochloride PO QD during week 1 and then BID during weeks 2-12. Treatment continues for 12 weeks in the absence of disease progression or unacceptable toxicity.

metformin hydrochloride: Given PO

pharmacological study: Correlative studies

laboratory biomarker analysis: Correlative studies
Eligibility criteria:
Inclusion Criteria:

History of prior colorectal adenomas within the past 3 years; only patients who have had adenomas endoscopically removed are eligible; documentation of colorectal adenomas must be determined via review of pathology reports
Body mass index (BMI) >= 30; rounded to the nearest whole integer
Eastern Cooperative Oncology Group (ECOG) performance status 0-1
Leukocytes ≥ 3,000/μL (>= 2,500/μL for African-American participants)
Absolute neutrophil count >= 1,500/μL (>= 1,000/μL for African-American participants)
Platelets >= 100,000/μL
Total bilirubin within normal institutional limits
Aspartate aminotransferase (AST) (serum glutamic oxaloacetic transaminase [SGOT])/alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase [SGPT]) =< 1.5 X institutional upper limit of normal (ULN)
Creatinine within normal institutional limits
Women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation
A serum pregnancy test must be performed and be negative in all women of childbearing potential within 2 weeks prior to starting treatment
Ability to understand and willingness to sign a written informed consent document

Exclusion Criteria:

History of colorectal cancer or other cancer(s) (except for non-melanoma skin cancers) within the last 3 years
Family history of hereditary intestinal polyp disorder (e.g., familial adenomatous polyposis [FAP], hereditary non-polyposis colorectal cancer [HNPCC], Putz-Jegher's disease)
Participants with diabetes
History of vitamin B12 deficiency or megaloblastic anemia
History of lactic acidosis
Diet or other medications for weight loss
Diseases associated with weight loss: anorexia, bulimia, or nausea
Treatment with medications that may increase metformin levels: cationic drugs, e.g., digoxin, amiloride, procainamide, trimethoprim, vancomycin, triamterene, and morphine
Treatment with other oral hypoglycemic agents
Participants who have undergone full bowel resection, ablation or other local therapies
Participants may not be receiving any other investigational agents
History of allergic reactions attributed to compounds of similar chemical or biologic composition to metformin
Participants with human immunodeficiency virus (HIV), cirrhosis of any cause, NASH (nonalcoholic steatohepatitis), or hepatitis (auto-immune or infectious)
Kidney disease or renal insufficiency (defined as serum creatinine > 1.4 mg/dL for females or > 1.5 mg/dL for males)
Metabolic acidosis, acute or chronic, including ketoacidosis

Uncontrolled intercurrent illness including, but not limited to:

Ongoing or active infection
Symptomatic congestive heart failure
Unstable angina pectoris
Cardiac arrhythmia
Psychiatric illness/social situations that would limit compliance with study requirements
Renal failure
Hepatic failure
Sepsis
Hypoxia
Pregnant or breastfeeding women are excluded
Participants anticipating elective surgery during the study period
Contraindication to colonoscopy/flexible sigmoidoscopy
Participants may not be using metformin, cimetidine (Tagament) furosemide (Lasix), nifedipine (Cardizem), Ranitidine (Zinetac or Zantac), digoxin (Lanoxin), Quinidine or any other drug contraindicated for use with metformin
Chronic alcohol use or a history of alcohol abuse
Participants with any medical psychosocial condition that, in the opinion of the investigator, could jeopardize participation in and compliance with the study criteria
Participants that regularly use aspirin (ASA), nonsteroidal anti-inflammatory drugs (NSAIDs), calcium, and cyclooxygenase (Cox)-2 inhibitors are not eligible for enrollment; however, patients that use aspirin 81 mg daily, or aspirin 325 mg, NSAIDs, calcium, or Cox-2 inhibitors at a frequency < 10 times per month are eligible