Omega-3 Fatty Acids in Preventing Joint Symptoms in Patients With Stage I-III Breast Cancer Receiving Anastrozole, Exemestane, or Letrozole

Inclusion Criteria:

* Women diagnosed with breast cancer stages I-III initiating first adjuvant AI therapy with any of the Food and Drug Administration- (FDA) approved AIs (anastrozole, exemestane, letrozole)
* Concurrent gonadotropin-releasing hormone (GnRH) agonist therapy is allowed
* Concurrent breast related radiation therapy is allowed
* Prior tamoxifen use is allowed
* Prior chemotherapy is allowed
* History of osteoarthritis and/or fibromyalgia is allowed
* Ability to understand and the willingness to sign a written informed consent document

Exclusion Criteria:

* Metastatic malignancy of any kind
* Rheumatoid arthritis and other types of autoimmune and inflammatory joint disease, with the exception of osteoarthritis and fibromyalgia
* AI use \> 2 weeks prior to study enrollment
* Known bleeding disorders
* History of diabetes mellitus, heart disease or TIA/stroke
* Current use of warfarin or other anticoagulants
* 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 situation that would limit compliance with study requirements
* Daily use of n-3 PUFA concentrates or capsules or regular or any other supplements that might interact with n-3 PUFA supplements within six months of study initiation; sporadic use of n-3 PUFA supplement may be eligible if there has been a 3-month washout period prior to randomization
* Pregnant or nursing women
* Known sensitivity or allergy to fish or fish oil
* Concurrent use of daily full dose aspirin (≥ 325 mg/day), nonsteroidal anti-inflammatory drugs (NSAIDs) or NSAID-containing products or steroids; one month washout period is required prior to randomization
* Unable to give informed consent
* In patients consenting for optional MRIs, any contraindication to MRI examination including but not limited to ferromagnetic metal in the body, pacemaker, or severe claustrophobia