This randomized phase II trial studies how well docosahexaenoic acid works in preventing recurrence in breast cancer survivors. Docosahexaenoic acid supplement may prevent recurrence in breast cancer survivors.

PRIMARY OBJECTIVES:

I. To determine whether treatment with docosahexaenoic acid (DHA) for 12 weeks at 1000 mg twice daily as compared to placebo reduces normal breast tissue levels of tumor necrosis factor-alpha (TNF-alpha) in overweight and obese patients with a history of stage I-III invasive breast cancer, ductal carcinoma in situ (DCIS), Paget's disease, lobular carcinoma in situ (LCIS), or proliferative benign breast disease.

SECONDARY OBJECTIVES:

I. To investigate the effect of DHA at 1000 mg twice daily on tissue biomarkers

• Change from the baseline in cyclooxygenase-2 (COX-2)/interleukin-1-beta (IL-1beta)/aromatase measured by quantitative real-time polymerase chain reaction (PCR).
• Change from the baseline in crown-like structures of the breast (CLS-B) measured by immunohistochemical techniques for cluster of differentiation (CD)68.
• Change from baseline in CLS-B index determined as follows: ([number of slides with evidence of at least one CLS-B]/[total number of slides examined]).
• Change from baseline in CLS-B/cm^2 defined as the number of CLS-B/cm^2. II. Evaluate age as a predictor of CLS-B and inflammatory biomarkers (TNF-alpha/COX-2/IL-1beta) at baseline and over the time of treatment.

III. Evaluate red blood cell (RBC) fatty acid level as a surrogate of compliance.

OUTLINE: Patients are randomized to 1 of 2 arms.

ARM I: Patients receive docosahexaenoic acid orally (PO) twice daily (BID) for 12 weeks.

ARM II: Patients receive placebo PO BID for 12 weeks.

Inclusion Criteria:

• Participants must have a history of histologically-confirmed stage I-III invasive breast cancer or ductal carcinoma in situ (DCIS), Paget's disease, lobular carcinoma in situ (LCIS), or proliferative benign breast disease
• No evidence of disease (in situ or invasive cancer that would normally be treated by resection) at trial entry as determined by the investigator
• >= 6 months from all previous breast cancer treatment (including surgery for invasive cancer, chest wall radiotherapy, chemotherapy, trastuzumab and endocrine therapy)
• Participants must have a body mass index (BMI) >= 25, defined as (weight in kilograms/[height in meters]^2)
• Participants must have adequate accessible breast tissue as determined by the treating physician, consisting of one breast unaffected by invasive cancer, which has not been radiated; a history of prior pre-invasive breast cancer or benign biopsy of this breast will be permitted
• Daily DHA consumption =< 200 mg/day in the month prior to screening estimated by an abbreviated DHA food frequency questionnaire
• Mammogram within no more than 6 months prior to the date of informed consent (normal/benign Breast Imaging-Reporting and Data System [BI-RADS] 1 or 2) and no further routine breast imaging planned during the course of the study (12 weeks DHA/placebo)
• Eastern Cooperative Oncology Group (ECOG) performance status must be =< 2 (Karnofsky >= 60%)
• Absolute neutrophil count >= 1,500/uL
• Platelets >= 75,000/uL
• White blood cells >= 3,000/uL
• Hemoglobin >= 10 g/dL
• Total bilirubin within 1.5 times the institution's upper limit of normal (ULN)
• Aspartate aminotransferase (AST) (serum glutamic oxaloacetic transaminase [SGOT])/alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase [SGPT]) within 1.5 times the institution's ULN
• Serum creatinine within 1.5 times the institution's ULN
• Pregnant women will be excluded; for women of childbearing potential; negative pregnancy testing within 72 hours prior to or on study visit #1 (day 0) and willingness to use adequate contraception during the study intervention OR post-menopausal defined as any one of the following 1) prior hysterectomy, 2) absence of menstrual period for 1 year in the absence of prior chemotherapy or 3) absence of menstrual period for 2 years in women with a prior history of chemotherapy exposure who were pre-menopausal prior to chemotherapy
• Willingness to comply with all study interventions and follow-up procedures including the ability to swallow the study drug
• Ability to understand and the willingness to sign a written informed consent document

Exclusion Criteria:

• Any type of active invasive cancer (excluding breast and non-melanoma skin cancer) within the preceding 18 months
• A history of histologically-confirmed bilateral invasive breast cancer
• Bilateral mastectomy
• Prior history or evidence of metastatic breast cancer
• Prior radiation therapy to the contralateral (unaffected) breast
• Prior history of contralateral (unaffected) breast augmentation with breast implant placement
• History of daily use of aspirin or non-steroidal anti-inflammatory drugs (NSAIDs) in the week preceding study entry
• History of DHA supplementation > 200 mg/day in the month preceding study entry
• History of autoimmune disorder or any illness that requires therapy with chronic steroids or immunomodulators
• History of therapeutic doses of anticoagulants including warfarin and low molecular weight heparin (e.g. for prior deep venous thrombosis and pulmonary embolism) in the preceding year
• Participants may not be receiving any other investigational agents during the study
• Women who have received cancer surgery, chemotherapy, biological therapy (e.g., trastuzumab), or radiotherapy for the treatment of any cancer within 6 months of study participation
• Women who are receiving endocrine therapy for breast cancer treatment or chemoprevention including tamoxifen, letrozole, anastrozole, fulvestrant, or exemestane at the time of screening
• Individuals with severe underlying chronic illness, such as uncontrolled diabetes; ongoing or active infection, psychiatric illness or social situations which in the opinion of the investigator would interfere with study participation
• History of allergic reactions attributed to compounds of similar chemical or biologic composition to DHA or corn/soy oil in placebo agent
• Pregnant, breastfeeding, or women of childbearing potential unwilling to use a reliable contraceptive method