• The primary outcome of the study is comparison of the change in proliferation (Ki67) and apoptosis (TUNEL) in cancerous tissue between the 2 groups. [ Time Frame: Conclusion of the study ] [ Designated as safety issue: No ]
  

Patient Population:

Pre and post menopausal women with breast cancer diagnosed by core needle biopsy scheduled to undergo breast cancer resection for an invasive carcinoma.

Objectives:

• To determine (by immunohistochemistry) whether specific cellular markers and gene products associated with breast carcinoma can be altered by soy therapy.
• To identify genes that can be altered by soy therapy in normal and neoplastic breast tissues by unbiased gene expression analysis using microarrays.
• To compare specific cellular markers and pathways (immunohistochemistry), and gene expression using microarrays in normal and cancerous breast tissue.

Study Design and Intervention Plan:

• Eligible patients will be consented at the time of visit with MSKCC breast surgeon and randomized to receive soy (soy protein supplementation 50 grams/day), or placebo (milk protein supplementation 50 grams/day) over the period until their surgery.
• The diagnostic biopsy (already available at time of appointment with MSKCC surgeon) will be analyzed by immunohistochemistry for proliferation (Ki67) and apoptosis (TUNEL). Additional immunohistochemistry will include HER2, TP53, cyclin D1, p27, BCL2, ER and PR.
• Excision of the breast carcinoma (lumpectomy or mastectomy) will proceed in standard fashion.
• The post-therapy excision specimen will be processed in a standard fashion. Pathologic features, margin status, and tumor size will be assessed by a light microscopic examination of histological sections. In addition to this routine processing, immunohistochemistry assays for proliferation (Ki67), apoptosis (TUNEL), HER2, TP53, cyclin D1, p27, BCL2, ER, and PR will be performed. For correlative biological studies pathologists will select approximately .5 cubic mm representative sections of the neoplastic tissues and normal adjacent breast tissue, which will be snap frozen for gene expression analysis using microarrays.