The purpose of this study is to examine breast cancers that express the protein (NIS) that may be found in malignant breast tissues and to evaluate proteins found in blood and their relationship to NIS, to test whether iodide can be concentrated by breast cells to possibly treat some breast cancers with radioactive iodine, and to calculate the amount of radioactive iodine entering breast cancer cells, how long your cancer retains the agent as well as how much is taken up by other organs, particularly the thyroid gland.

To demonstrate iodide uptake capacity of breast cancer metastases by imaging women with iodide radioisotope (123I) and calculating potential ablative dose of radioactive iodide (131I).

Inclusion Criteria:- Only women diagnosed with breast cancer

• 18 years of age or older
• From whom informed consent can be obtained
• Patient is able to provide a fluid (e.g. cyst fluid)
• Patient with blood test that shows protein may allow iodide to accumulate in breast tissue
• Patient who's breast cancer cells accumulated I123 and held on to it for 24 hours Exclusion Criteria:- Males
• Children

Eligibility criteria include histological proof of invasive breast cancer and current radiological evidence of metastatic disease.