This phase II trial is studying how well giving acetylsalicylic acid together with eflornithine works in treating patients at high risk for colorectal cancer. Chemoprevention is the use of certain drugs to keep cancer from forming. The use of acetylsalicylic acid and eflornithine may prevent colorectal cancer.

PRIMARY OBJECTIVES:

I. The proportion of subjects with an adenoma recurrence at the 1-year follow-up colonoscopy exam. This adenoma recurrence rate for difluoromethylornithine (DFMO) (eflornithine) + aspirin will be compared to double placebo to see if there is improvement in the adenoma recurrence rate in this patient population.

SECONDARY OBJECTIVES:

I. To determine the relative tolerability and safety of the treatment regimens administered for 12 months.

II. To determine the effect of the study drugs (aspirin [acetylsalicylic acid] + DFMO) and placebo with respect to proliferation (Ki67 labeling index), apoptosis (caspase-3 expression assay), and drug effect markers (COX-1, -2, polyamines, PGE2) from adenomas, aberrant crypt focus (ACF) and normal-appearing mucosa using pre- and 12-month post-intervention tissue biopsy samples.

III. To estimate the percentage change in rectal ACF number, as determined by magnifying colonoscopy in subjects treated for 12 months with placebo or study drugs (aspirin +DFMO) by comparing % change in drug versus placebo arms.

IV. To characterize ACF based on three criteria (ACF size [crypt number < 50 or >= 50], crypt morphology characteristics, and histology) of ACF and to correlate such characteristics with the intervention (vs placebo). Also, to evaluate the natural history of ACF over 1-year on placebo.

V. To correlate the 12-month measurements of ACF size (# crypts/ACF), number, morphology, and histopathology with the adenoma recurrence data at 12 and 36 months; correlate the 12-month % (and actual) change in ACF size and number with the 12- and 36-month adenoma recurrence rate; and correlate the adenoma recurrence data at 1 year with the adenoma recurrence data at 3 years.

TERTIARY OBJECTIVES:

I. To explore the effects of the study agents on a focused panel of tissue biomarkers in pre- and post-intervention biopsy samples from recurrent adenomas, rectal ACF, and adjacent normal-appearing mucosa among subjects enrolled in the phase II clinical trial.

II. To determine if cleaved capase-3 expression can improve the detection of apoptotic cells by recognizing cellular commitment to apoptosis prior to late nuclear morphologic features and correlate with apoptotic regulatory proteins, histology, and treatment response.

III. To determine the effects of aspirin on its biochemical targets COX-1, -2, and prostaglandin E2, and polyamine levels in subjects receiving DFMO.

IV. To examine COX-2-dependent genes (i.e., Bcl-2 and DR5) in adenomas and ACF that have been shown to regulate the intrinsic mitochondrial and extrinsic death receptor-mediated apoptotic pathways in vitro and in vivo.

V. To perform expression profiling of adenomas or ACF and to relate such date to ACF histology, size/morphology, modulation by chemopreventive agents, and subsequent adenoma recurrence rates.

OUTLINE: Patients are randomized to 1 of 2 treatment arms.

ARM I: Patients receive acetylsalicylic acid orally (PO) once daily and eflornithine PO twice daily on days 1-28.

ARM II: Patients receive placebo PO three times daily on days 1-28.

Treatment repeats every 28 days for 12 months in the absence of disease progression or unacceptable toxicity.

After completion of study treatment, patients are followed at 6, 12, and 36 months.

Inclusion Criteria:

• Current or prior advanced adenomas
• Advanced adenomas are defined as subject with polyps >= 1 cm, tubulovillous adenomas (25-75 percent villous features), villous adenomas (> 75 percent villous), or high-grade dysplasia
• Prior colon cancer (>= 3 years out from invasive cancer)
• Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0 or 1
• Ability to under and the willingness to sign a written informed consent document
• Willingness to provide mandatory tissue for research purposes
• Negative pregnancy test =< 7 days prior to randomization
• Hemoglobin (Hgb) within normal limits for institution/lab
• Platelet count >= 100,000/ul
• White blood cell count (WBC) >= 3,000/ul
• Alanine aminotransferase (ALT) =< 2 x institutional upper limit of normal (ULN)
• Aspartate aminotransferase (AST) =< 2 x institutional ULN
• Total bilirubin =< 1.5 x institutional ULN
• Serum calcium =< institutional ULN
• Serum creatinine =< 1.5 x institutional ULN
• Colonoscopy =< 45 days prior to randomization with removal of all adenomas or polyps >= 2 mm in size

Exclusion Criteria:

• Any history of current or prior rectal cancer
• 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 pills
• Bleeding diathesis
• New diagnosis of carcinoma
• History of hypersensitivity to COX-2 inhibitors, sulfonamides, nonsteroidal antiinflammatory drugs (NSAIDs), salicylates, or ursodeoxycholic acid
• 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 subject a poor protocol candidate, in the opinion of the treating physician
• Total colectomy
• Patients with a colostomy
• History of pelvic or rectal radiation therapy
• History of invasive carcinoma =< 5 years (except subjects with Dukes A/B1 carcinoma =< 5 years prior to pre-registration or any stage of colon cancer if >= 3 years post surgical resection)
• Acute liver disease, unexplained transaminase elevations, or elevated serum calcium
• History of allergic reactions attributed to compounds of similar chemical composition to the study agents
• 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
• New diagnosis of invasive carcinoma
• Use of non-study investigational agent(s) =< 3 months prior to randomization
• Chemotherapy =< 6 months prior to randomization (Note: topical chemotherapy will be assessed on a case-by-case basis)
• Pregnant women
• Nursing women
• Men or women of childbearing potential who are unwilling to employ adequate contraception
• Regular use of NSAIDs =< 6 weeks prior to randomization, defined as a frequency of 7 consecutive days (1 week) for > 3 weeks (Exception: low dose aspirin [81 mg] for those subjects who are chronic users of aspirin prior to the beginning of the study)