Inclusion Criteria:

- Participants must have microscopic confirmation of adenocarcinoma of the prostate
within three months of randomization; clinical stage T1 and T2 a, b, or c are allowed

- Participants' prostate cancer must be confined to the prostate (in the clinical
judgment of the treating physician)

- Participants must be candidates for prostatectomy

- Participants must have ECOG performance status =<1 (Karnofsky >= 70%)

- WBC within normal limits

- Platelets >= 100 K/uL

- Hemoglobin >= 10 g/dL

- TSH =< 4.20 uIU/mL

- Free T4 =< 12.5 ng/dL

- Bilirubin within upper limit of normal

- Aspartate aminotransferase (AST) =< 1.5 x upper limit of normal

- Creatinine =< 2.0 mg/dL

- Serum calcium: within institutional normal limits

- Participants must agree to stop taking NSAIDS during the course of the study,
however, low dose aspirin (< 100 mg/day) will be allowed; no wash out period is
required

- Participants must be willing to discontinue consuming soy products and ingesting
vitamin supplements while participating in this study

- The effects of cholecalciferol and genistein on the developing human fetus at the
recommended therapeutic doses are unknown; for this reason, participants must agree
to use adequate contraception (hormonal or barrier method of birth control;
abstinence) for the duration of study participation

- Participants must have the ability to understand and sign a consent form indicating
the investigational nature of the treatment and its potential risks

Exclusion Criteria:

- Participants may not have received any prior therapy for prostate cancer including:
chemotherapy, hormonal therapy, brachytherapy, or external radiation

- Participants may not be receiving concurrent systemic therapy for other cancers

- Participants may not be receiving any other investigational agents

- Participants may not be taking the following p450 inducers and inhibitors:
carbamazepine, clarithromycin, fluconazole, fosphenytoin, itraconazole, ketoconazole,
phenobarbital, phenytoin, rifabutin, rifampin

- Participants took finasteride or dutasteride within 6 months of the pre-randomization
biopsy, are currently taking finasteride or dutasteride, or are planning on taking
these agents during study participation

- Participants with a history of allergic reactions attributed to genistein or placebo,
or compounds of similar chemical or biologic composition

- Participants with 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

- Participants with a history of thyroid disease, nephrolithiasis and/or sarcoidosis