Low-Dose Tamoxifen Citrate in Reducing Breast Cancer Risk in Radiation-Induced Cancer Survivors

You may be eligible if

• Exposure to radiation therapy (RT) delivered to the chest, axilla, and/or supraclavicular areas at a cumulative dose of 12 Gy or more by age 40 years; in addition, patients who received total body irradiation by age 40 may be considered
• No evidence of active disease from their primary cancer for at least 2 continuous years prior to registration; the indication for RT is not specified but cannot be for primary breast cancer; common examples include, but are not limited to: lymphoma, leukemia, sarcoma, and Wilms tumor occurring in pediatric patients, and lymphoma, leukemia, and sarcoma occurring in young adults; primary cancer therapy must have been completed at least 6 months prior to registration
• Well-defined menopausal status falling into one of the following categories:
• * Premenopausal, defined as age at registration 45 years old or younger with regular monthly period for at least 6 consecutive months prior to registration
• * Postmenopausal, defined as continuous absence of menstruation for 12 months OR status-post bilateral oophorectomy OR follicle stimulating hormone (FSH) level in the postmenopausal range
• * Non-melanoma cancers of the skin
• * Thyroid cancer
• * Cervical cancer confined to the cervix or cervical intraepithelial neoplasia (CIN)
• * Ductal carcinoma in situ (DCIS) or breast intraepithelial neoplasia (IEN) (includes atypical hyperplasia and lobular carcinoma in situ \[LCIS\]), or
• * Superficial or non-invasive transitional cell carcinoma of the bladder
• For women with a prior history of DCIS or breast IEN, only one breast could have been involved and all therapy must have been completed at least 6 months prior to registration; in addition women with a prior history of invasive breast cancer may also be eligible, as long as only one breast was involved, they were diagnosed at least 2 years prior to study entry, and therapy was completed at least 6 months prior to study entry
• Bilateral breast implants or status-post bilateral prophylactic mastectomy
• Evidence of malignant breast disease on any form of breast imaging; the study only requires annual mammography; however, annual breast magnetic resonance imaging (MRI) is considered standard of care in this patient population (per Children's Oncology Group \[COG\] or National Comprehensive Cancer Network \[NCCN\] follow-up guidelines), and breast ultrasound may be indicated if a palpable lesion is detected on screening clinical breast exam; abnormal imaging may require additional radiographs and/or breast biopsy; patients who are found to have benign breast disease with or without atypia may continue on study as long as there is no evidence of malignancy; if there is evidence of malignancy, and only one breast is involved, they may be reapproached 6 months after completion of therapy for consideration of the trial
• Baseline categorical mammographic density scored as BIRAD 1, or extremely fatty, in both breasts; if the patient has a prior history of IEN (DCIS, LCIS, or atypical hyperplasia), the contralateral breast must not have a mammographic density score of BIRAD 1; this determination will be made at the local site
• Current or recent use (within 6 months of registration or baseline mammogram, whichever is first) of any of the following: systemic hormone replacement therapy (includes oral or transdermal formulations); Vagifem and Estring, two formulations of locally applied vaginal estrogen associated with minimal systemic absorption, may be allowed; other estrogen-containing vaginal creams, while not an exclusion, should be avoided whenever possible; patients with a history of hormone modifying herbal supplements are eligible, but patients will be asked to avoid their use after on study
• Current or recent use (within 6 months of registration or baseline mammogram, whichever is first) of any of the following: hormonal forms of contraception (includes oral, transdermal, implanted, and injectable formulations): selective estrogen receptor modifiers; aromatase inhibitors; GnRH analogs; androgens or antiandrogens
• Concurrent use of warfarin and strong inhibitors or CYP2D6 will not be allowed
• A personal history or a strong family of thromboembolism, including deep venous thrombosis (DVT), pulmonary embolus (PE), or cerebrovascular accident (CVA); a personal history of transient ischemic attack (TIA) or retinal vein thrombosis will also not be allowed; in addition, patients with a condition known to increase hypercoagulability, such as Factor V Leiden disease, will be excluded; patients with atrial fibrillation will be excluded, due to risk of CVA, but patients with coronary artery disease or congestive heart failure without atrial fibrillation will be allowed to participate
• Current intrauterine pregnancy or plans to become pregnant within two years; in addition, currently nursing mothers will be excluded
• Serum creatinine \> 2X the institutional norm
• Total bilirubin \> 2X the institutional norm
• Serum glutamic oxaloacetic transaminase (SGOT) or serum glutamic pyruvic transaminase (SGPT) \> 2X the institutional norm
• Unable to provide consent