• rate of progression to prostate cancer at one year in men treated with Polyphenon E (200 mg EGCG bid) following diagnosis of HGPIN. [ Time Frame: 12 months ] [ Designated as safety issue: No ]
  
• safety of Polyphenon E (200 mg EGCG bid for one year) in men with HGPIN [ Time Frame: 12 months ] [ Designated as safety issue: Yes ]
  
• the effect of Polyphenon E treatment on quality of life in men diagnosed with HGPIN. Evaluate the effect of Polyphenon E treatment on LUTS and QOL in men diagnosed with HGPIN. [ Time Frame: 12 months ] [ Designated as safety issue: No ]
  

• the effect of Polyphenon E treatment on levels of ABCA5 in urine and PCADM-1 in serum [ Time Frame: 6 and 12 months ] [ Designated as safety issue: No ]
  
• Explore the effects of Polyphenon E on the fundamental molecular pathways contributing to chemopreventive activity of Polyphenon E in the prostate [ Time Frame: 12 months ] [ Designated as safety issue: No ]
  

Inclusion Criteria:

• Men with a diagnosis of HGPIN in a minimum of 1 of 12 cores from a biopsy performed within three months of study entry; the diagnosis of HGPIN must be confirmed by the site pathologist
• Prostate biopsy with a minimum of 12 cores performed within three months of study entry that shows no evidence of cancer; absence of cancer must be confirmed by the site pathologist
• 30−80 years of age at the time of registration
• PSA ≤10 ng/ml
• Omnivorous diet
• ECOG performance status 0−2
• Participants must have normal organ and marrow function as demonstrated by the following parameters being within normal institutional limits: complete blood count (CBC); liver function tests (LFTs; albumin, total and direct bilirubin, alkaline phosphatase, AST, ALT, and total protein), PT/PTT, and LDH; serum creatinine <1.5 mg/dl or measured creatinine clearance 60 cc/min
• Absence of consumption of toremifene citrate, finasteride, testosterone, dehydroepiandrosterone (DHEA) or other testosterone-like supplements or medications which have known impact on PSA within 30 days of registration, or dutasteride within 90 days of registration
• Absence of consumption of any nutritional or herbal supplements, including herbs, green tea polyphenols and high-dose antioxidants
• No or low regular tea consumption (no more than three (3) servings of hot tea or six (6) servings of iced tea per week)
• Willing to discontinue current vitamin/mineral supplement use and substitute with a standard multivitamin supplement provided for the study
• Willing to use an effective method of contraception, if the partner is of child-bearing age, while on study
• Willing to comply with proposed visit and treatment schedule
• Able to understand and willing to sign a written informed consent document

Exclusion Criteria:

• Evidence of prostatitis or urinary tract infection; men may be enrolled 30 days after completion of treatment, provided all other eligibility criteria are met
• Current or prior history of prostate cancer or other malignancies (exceptions include non-melanoma skin cancer or other cancer with no evidence of tumor recurrence five years after definitive treatment)
• History of renal or hepatic disease, including history of hepatitis B, C or delta
• Participation in any other investigational study or use of any other investigational agents within 30 days of study entry
• History of allergic reactions attributed to tea or other compounds of similar chemical or biologic composition to Polyphenon E or the inactive components present in Polyphenon E and placebo capsules.
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or any psychological, familial, sociological or other concomitant condition that would not allow adequate compliance with the study protocol