Inclusion Criteria:

- Current or prior advanced adenomas. Participants with advanced adenomas are defined
as participants who have polyps >= 1 cm, who have tubulovillous adenomas (25-75
percent villous features), who have villous adenomas (>75 percent villous), or who
have severe dysplasia

- Prior curatively resected Tumor, Node, Metastasis (TNM) stage II and III colon cancer
>= 3 years out from treatment by surgery with/without adjuvant chemotherapy; NOTE:
patients with stage I (T1,2 N0) colon cancer treated by endoscopic or surgical
therapy are eligible at anytime after such therapy; patients with prior stage IV
disease must be >= 5 years status post surgical resection of all metastatic disease

- Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0 or 1

- Ability to understand and the willingness to sign a written informed consent document

- Willingness to discontinue regular usage of calcium supplements; Exception:
multi-vitamin; regular use defined as a frequency of 7 consecutive days for > 3 weeks

- Willingness to provide mandatory tissue and blood for protocol specified research;
residual tissue and/or blood may be used for future research Negative pregnancy
test =< 7 days prior to registration/randomization

- Hemoglobin (Hgb) >= 12.0 g/dL (women), >= 13.5 g/dL (men) at Mayo Clinic or within
normal limits at an outside laboratory

- Platelet count >= 100,000/ul

- White blood cells (WBC) >= 3,000/ul

- Alanine aminotransferase (ALT) within institutional limits of normal

- Alkaline phosphatase within institutional upper limit of normal (ULN)

- Aspartate aminotransferase (AST) within institutional limits of normal

- Total bilirubin within institutional limits of normal

- Serum calcium =< institutional ULN

- Serum creatinine =< 1.5 x institutional ULN

- >= 5 rectal ACF detected by chromoendoscopy =< 45 days prior to
registration/randomization

- Endoscopy =< 45 days prior to registration/randomization; Note: All adenomas or
polyps will be removed according to institutional standards of care, and the cecum
must visualized; this may be done at the same time as the chromoendoscopy

Exclusion Criteria:

- Any history of rectal cancer; Exception: transanal excision without radiation

- Known diagnosis of colon heritable cancer syndrome (Familial adenomatous polyposis
[FAP], hereditary nonpolyposis colorectal cancer [HNPCC]) or inflammatory bowel
disease (Crohn's disease, ulcerative colitis)

- Inability to swallow capsules

- Bleeding diathesis

- Any invasive malignancy =< 5 years prior to pre-registration;

- Exceptions:

- patients with nonmelanoma skin cancers that were treated with simple excisional
biopsy or stage I (T1,2 N0)

- colon cancer treated by endoscopic therapy or surgery are eligible

- History of gastroduodenal ulcers documented =< 1 year

- Known inability to participate in the scheduled follow-up tests

- Significant medical or psychiatric problems which would make the participant a poor
protocol candidate, in the opinion of the treating physician

- Total colectomy

- Colostomy

- History of pelvic or rectal radiation therapy

- History of liver disease

- Uncontrolled intercurrent illness including, but not limited to, ongoing or active
infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac
arrhythmia

- Concomitant corticosteroids or anticoagulants needed on a regular or predictable
intermittent basis

- Use of non-study investigational agent(s) =< 3 months prior to preregistration

- Chemotherapy =< 6 months prior to pre-registration; Note: Topical chemotherapy will
be assessed on a case-by-case basis

- Any of the following: * Pregnant women * Nursing women * Men or women of childbearing
potential who are unwilling to employ adequate contraception Note: This study
involves an investigational agent whose genotoxic, mutagenic, and teratogenic effects
on the developing fetus and newborn are unknown

- Over-the-counter green tea or green tea extract use =< 6 weeks prior to
pre-registration; consumption of over the counter green tea extracts or drinking of
green tea is not permitted during the treatment portion of this trial

- Regular use of nonsteroidal anti-inflammatory drugs (NSAIDs) =< 6 weeks prior to
pre-registration; regular use of NSAIDs is defined as a frequency of 7 consecutive
days (1 week) for > 3 weeks; participant must abstain from regular use of NSAIDs for
the duration of the study; Exception: low dose aspirin (81 mg) for those participants
who are chronic users of aspirin prior to the beginning of the study

- Use of non-study investigational agents while on study