Tamoxifen Citrate in Treating Patients With Metastatic or Recurrent Breast Cancer

Inclusion Criteria:

Histologically confirmed adenocarcinoma of the breast

Stage III (locally advanced), metastatic, or recurrent disease
Deemed not resectable

Estrogen-receptor and/or progesterone-receptor positive disease

Receptor status is based on most recent results
Measurable or non-measurable disease
ECOG performance status 0-2
History of central nervous system (CNS) metastasis allowed provided it has been treated (surgery, radiotherapy, or radiosurgery) within the past 4 weeks and does not require medications to control symptoms
Total bilirubin ≤ 1.5 times upper limit of normal (ULN)
Alanine transaminase (ALT) and aspartate transaminase (AST) ≤ 2.5 times ULN (≤ 5 times ULN if liver metastases present)
Negative pregnancy test
Fertile patients must use effective nonhormonal contraception
Disease-free of prior invasive malignancies for ≥ 5 years with the exception of curatively-treated basal cell or squamous cell carcinoma of the skin or carcinoma in situ of the cervix
Prior chemotherapy, trastuzumab, or bevacizumab in the adjuvant setting allowed provided it has been completed ≥ 4 weeks before study therapy; other prior non-hormonal investigational agents in the adjuvant setting must have been completed at least 4 weeks prior to study registration and should be discussed with the study PI
Prior tamoxifen as adjuvant treatment is allowed as long as the patient did not have disease relapse or progression while on adjuvant tamoxifen or within 4 weeks of last dose
Treatment in the advanced setting must have been completed at least 2 weeks prior to study initiation
Prior aromatase inhibitors (e.g., anastrozole, letrozole, exemestane, aminoglutethamide) are allowed in the adjuvant or metastatic setting

At least 2 weeks since prior and no concurrent medications that are strong to moderate inhibitors of CYP2D6 and may alter tamoxifen citrate metabolism including, but not limited to, any of the following:

Paroxetine (Paxil)
Fluoxetine (Prozac)
Bupropion (Wellbutrin)
Quinidine (Cardioquin)

Concurrent radiotherapy to painful sites of bone disease or areas of impending fractures allowed provided the following criteria are met:

Radiotherapy was initiated before study entry
Sites of measurable or non-measurable disease are outside the radiotherapy port
Recovered from prior radiotherapy

Exclusion Criteria:

Pregnant or nursing
Concurrent chemotherapy
Leptomeningeal disease
Non-protocol concurrent hormonal therapy
Medical or psychiatric conditions that would interfere with protocol compliance, the ability to provide informed consent, assessment of response, or anticipated toxicities
Prior tamoxifen for advanced disease
More than 2 lines of non-hormonal treatment in the locally advanced or metastatic setting, including trastuzumab (Herceptin), bevacizumab, or other biologics

Starting bisphosphonate therapy while receiving treatment on this study

Patients who have begun receiving bisphosphonate therapy prior to registration may continue at the same intervals used prior to study registration