Inclusion Criteria:
* Participants with a clinical diagnosis of cirrhosis based on the investigators evaluation, confirmed by ANY ONE of the three following methods to define cirrhosis:
* Established cirrhosis on liver biopsy (Meta-analysis of Histological Data in Viral Hepatitis \[METAVIR\] F4);
* Ultrasound, CT or MRI findings consistent with cirrhosis; nodular appearing liver with or without evidence of portal hypertension
* Transient elastography (FibroScan) with a result \> 12.5 kPa Etiology of cirrhosis will not be considered in determining inclusion in the study
* Participant is able and willing to comply with study procedures, and signed and dated informed consent is obtained
* Participant agrees to consume no more than 2 cups of green tea per day and refrain from taking supplements or foods labeled as containing green tea
* Participant must be aged \>= 18 years. Because no dosing or adverse event (AE) data are currently available on the use of Polyphenon E in participants \< 18 years of age, children are excluded from this study but will be eligible for future pediatric trials, if applicable
* Eastern Cooperative Oncology Group (ECOG) performance status =\< 1 (Karnofsky \>= 70%)
* Platelets \>= 75,000 / uL
* Hemoglobin \>= 8 g/dL
* Serum creatinine OR measured or calculated creatinine clearance within normal institutional limits; glomerular filtration rate (GFR) can also be used in place of creatinine or creatinine clearance (CrCl) within normal institutional limits as adjusted for age and sex
* Serum direct bilirubin within normal institutional limits
* Aspartate aminotransferase (AST) (serum glutamic oxaloacetic transaminase \[SGOT\]) and alanine aminotransferase (ALT) (serum glutamic pyruvic transaminase \[SGPT\]) =\< 2.5 X upper normal level (UNL)
* Albumin \>= 3.0 mg/dL
* International normalized ratio (INR) =\< 1.3
* Ascites absent
* Encephalopathy absent
* Only participants found to express high levels (immunohistochemistry \[IHC\] score 3 and above) of gamma-OHPdG (gamma-OHPdG-high HCC) in baseline or archival liver biopsy will be registered to receive Polyphenon E treatment
* Participant is able to undergo radiographic evaluation with ultrasound, CT, or MRI
* The effects of Polyphenon E on the developing human fetus at the recommended therapeutic dose are unknown; for this reason, women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence); contraception must be used 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 study physician immediately; female participants of childbearing potential should have a negative urine or serum pregnancy test within 72 hours prior to receiving the first dose of study medication (if a urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required)
Exclusion Criteria:
* Participant has confirmed HCC by ultrasound/CT/MRI; participants who have previously had HCC but have been treated and have been recurrence free for 5 years are eligible
* Participant has or has had other cancer(s) within 3 years of study; however, in situ breast, in situ cervical, and basal cell/squamous cell skin cancers are allowed; participant with active, other cancer that requires systemic therapy will be excluded from this study; participant with early stage cancer that requires local therapy, such as cervical ablation for early stage cervical cancer, are allowed to be registered in the study and are allowed to receive local therapy
* Inability to swallow capsules
* Participant has a known diagnosis of mental incapacitation that may affect their ability to consent and be compliant with the protocol
* Participant has ever experienced one or more hepatic decompensation events or a history of decompensated liver disease as listed below:
* Clinical ascites
* Variceal bleeding documented by endoscopy
* Spontaneous bacterial peritonitis documented by positive culture
* Hepatic encephalopathy
* Hepatorenal syndrome (type 1 or 2)
* Porto-pulmonary hypertension
* Hepato-pulmonary hypertension
* Any liver-related event which led to a hospitalization or a grade 4 event
* Participant has an underlying predisposition to gastrointestinal (GI) or rectal bleeding are considered ineligible for study participation
* History of allergic reactions attributed to compounds of similar chemical composition to Polyphenon E (or green tea); note that participants who are unable to tolerate intravenous contrast for CT scans should have MRIs or ultrasounds during the study instead of CT scans
* Participant is receiving any other investigational agents
* Participants have taken supplements or foods that are labelled as containing green tea for 8 weeks before start of treatment
* 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; hepatitis b virus (HBV) and hepatitis C virus (HCV) infections are allowed
* Green tea has been consumed by humans for thousands of years and teratogenic or abortifacient effects have not been reported; however, subjects in this study will take high doses of Polyphenon E; the teratogenic or abortifacient effects of high dose Polyphenon E is unknown; therefore pregnant women are excluded from this study; because there is an unknown but potential risk for AEs in nursing infants secondary to treatment of the mother with Polyphenon E, breastfeeding should be discontinued if the mother is treated with this study agent
