RATIONALE: Diagnostic procedures, such as PET scans, may help in learning how well hormone therapy and trastuzumab work to kill breast cancer cells and allow doctors to plan better treatment.

PURPOSE: This clinical trial is studying how well PET scans work in assessing response to treatment in patients receiving hormone therapy or trastuzumab for breast cancer.

OBJECTIVES:

• Correlate the percent change in fludeoxyglucose F 18 (FDG)-positron emission tomography (PET) standardized uptake value (SUV) and percent change in cell proliferation (as assessed by tumor biopsy) during hormonal therapy with tumor response in patients with hormone receptor-positive (estrogen receptor or progesterone receptor) breast cancer.
• Correlate the percent change in FDG-PET SUV and percent change in cell proliferation (as assessed by tumor biopsy) during treatment with trastuzumab (Herceptin®) with tumor response in patients with HER-2/neu-positive breast cancer.
• Compare the association between two-week changes in cell proliferation rate (as measured by FDG-PET and biopsy) in patients treated with an aromatase inhibitor or trastuzumab.

OUTLINE: Patients are assigned to 1 of 2 groups according to therapy.

• Group 1 (patients receiving hormonal therapy): Patients undergo fludeoxyglucose F 18-positron emission tomography (FDG-PET) scan and may also undergo 16α-fluoroestradiol F 18 (FES)-PET scan at baseline (prior to beginning therapy) and FDG-PET scan 2 weeks after beginning therapy.

Blood samples are collected at baseline and at 3 and 6 months after beginning aromatase inhibitor therapy. The blood samples are examined for hormone levels, including estradiol, estrone, testosterone, follicle-stimulating hormone, and sex hormone-binding globulin.

• Group 2 (patients receiving HER-2/neu targeted therapy): Patients undergo biopsy and FDG-PET scan at baseline (prior to beginning therapy) and FDG-PET scan 1-2 weeks after beginning therapy.

Some patients undergo a core-needle biopsy 2 weeks after beginning therapy. Biopsies are assessed for the following markers: proliferative rate (Ki67), estrogen receptor, progesterone receptor, HER-2/neu, epidermal growth factor receptor, androgen receptor, and topoisomerase II.

After completion of study therapy, patients are followed periodically for 6 months.

PROJECTED ACCRUAL: A total of 40 patients will be accrued for this study.

DISEASE CHARACTERISTICS:

• Newly diagnosed breast cancer with 1 of the following:

  • Hormone receptor-positive disease and planning to receive treatment with neoadjuvant aromatase inhibitor and ovarian suppression therapy (if premenopausal)
  • Recurrent and/or metastatic hormone receptor-positive disease and planning to receive treatment with an aromatase inhibitor and ovarian suppression therapy (if premenopausal)
  • Metastatic HER-2/neu-positive disease and planning to receive treatment with neoadjuvant trastuzumab (Herceptin®)
  • Recurrent HER-2/neu-positive disease and planning to receive treatment with trastuzumab (Herceptin®)

• Tumor must be accessible for biopsy and assessable for response

  • Tissue block must be available for review of experimental markers or patient must be willing to undergo biopsy

• Evaluable disease by FDG-PET scan

• Available for positron emission tomography (PET) imaging with a clinical indication for PET scan

  • May aslo be enrolled on an experimental nuclear imaging study of 16α-fluoroestradiol F 18-PET scan (if hormone positive)

• Concurrently receiving treatment (hormonal or other) for breast cancer

• Hormone receptor status:

  • Not specified

PATIENT CHARACTERISTICS:

• Female or male
• Postmenopausal or premenopausal
• Life expectancy ≥ 2 months
• No uncontrolled diabetes mellitus or other comorbidity that would preclude imaging
• Not pregnant
• Negative pregnancy test
• Able to tolerate scanning (e.g., no claustrophobia or severe pain)

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• Concurrent participation on another clinical study or other imaging studies allowed

Patients with primary, recurrent or metastatic breast cancer that is either hormonal receptor positive or HER-2/neu positive.