Tamoxifen to Treat Barrett's Metaplasia

Inclusion Criteria: * Biopsy-proven Barrett's esophagus that is non-dysplastic or with low grade dysplasia. * At least 18 years of age. * ECOG performance status ≤ 2 * Normal bone marrow and organ function as defined below: * Absolute neutrophil count ≥1,500/mcl * Platelets ≥ 100,000/mcl * AST(SGOT)/ALT(SGPT) ≤1.5 x IULN * Serum creatinine within normal institutional limits or less than the lower limit of normal institutional limits; or creatinine clearance ≥ 60 mL/min/1.73 m2 for patients with creatinine levels above institutional normal * Women of childbearing 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. Should a woman become pregnant or suspect she is pregnant while participating in this study, she must inform her treating physician immediately. * Ability to understand and willingness to sign an IRB approved written informed consent document. Exclusion Criteria: * Prior history of esophageal cancer. * Prior history or current use of tamoxifen or anti-estrogen therapy. * A history of allergic reactions attributed to compounds of similar chemical or biologic composition to tamoxifen. * Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements. * Pregnant and/or breastfeeding. Female patients must have a negative urine pregnancy test within 14 days of study entry. * Known HIV-positivity and on combination antiretroviral therapy because of the potential for pharmacokinetic interactions with tamoxifen. Appropriate studies will be undertaken in patients receiving combination antiretroviral therapy when indicated. * Taking medications known to affect drug metabolism via the CYP3A4, CYP2C9, or CYP2D6 pathways. * History of blood clots (i.e. pulmonary embolism, DVTs). * Concurrent use of anticoagulants (i.e. Coumadin/warfarin).