Study of Docosahexaenoic Acid (DHA) in Triple Negative Breast Cancer Survivors

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 \>= 7…