Phase II Study of Isoflavone G-2535 (Genistein) in Patients With Bladder Cancer

Inclusion Criteria:

* Participants eligible for this study will have been evaluated by diagnostic office cystoscopy and found to have a bladder tumor; enrollment (signing of the consent form) must be within 60 days of pre-study cystoscopy demonstrating bladder tumor; the participant should have no evidence of distant metastasis and the primary tumor may represent either an initial diagnosis or recurrent disease of any clinical stage. Study participants must also be candidates for either subsequent cystoscopy/transurethral resection of bladder tumor (TURBT) or complete or partical cystectomy; histologic diagnosis is not required for enrollment; pre-enrollment diagnostic cystoscopy must be at least 45 days after treatment of the bladder with other agents such as BCG (participants with recurrent disease)
* ECOG performance status 0 or 1
* 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
* Ability to understand and the willingness to sign a written informed consent document
* WBC \>= 3000/mm\^3
* Platelets \>= 100,000mm\^3
* Hemoglobin \>= 10 g/dL
* Bilirubin =\< 1.4 mg/dl
* AST =\< 3x normal
* Creatinine =\< 2.0mg/dl
* Serum calcium =\< 10.2 mg/dl,
* Amylase =\< 3 x normal
* Na \>= 125 and =\< 155 mmol/L
* K \>= 3.2 and =\< 6 mmol/L
* Cl \>= 85 and =\< 114 mmol/L
* CO2 \>= 11 mEQ/dL
* TSH within 1.3 x the upper range of normal and normal T4
* Females of child-bearing potential must have a negative pregnancy test; patients who have had a bilateral oophorectomy, hysterectomy, are greater than 1 year since their last menses, or are greater than 51 years of age are not considered to be of child-baring potential
* Participants must agree to stop soy supplements before enrolling in the study
* Patients must agree to stop taking NSAIDS before enrolling in the study; patients may, however, take cardioprotective doses of aspirin equal to or less than 81mg per day

Exclusion Criteria:

* Participant may not have received other treatment for bladder cancer between the pre-enrollment cystoscopy and subsequent surgery
* Participants may not be receiving any other investigational agents
* Participant may not have received prior pelvic irradiation for any reason
* Participant may not be receiving concurrent systemic cancer treatment for other cancers
* Participant may not be taking concurrent soy supplements while on the study medication
* Participant may not be taking concurrent NSAIDS (aspirin doses of =\< 81 mg acceptable) while on the study medication
* Participant may not be taking thyroid medications
* History of allergic reactions attributed to compounds of similar chemical or biologic composition to genistein, soy isoflavones or other allergies to soy-based products will render a participant ineligible
* Uncontrolled concurrent illness will render a participant ineligible including, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, unregulated cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements
* Women may not be pregnant or lactating; the effects of G-2535 on the developing human fetus at the recommended therapeutic dose are unknown; for this reason 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 should inform her treating physician immediately