The purpose of this study is to find out if using probiotics will help the body's immune system react to breast cancer. New studies showed that diverse species of bacteria inside the bowel might help improve immune system, particularly the ability of immune system to recognize cancer. This study will investigate how probiotics will affect the subjects' immune system on breast cancer.

Inclusion Criteria:

• Post-menopausal females ≥ 18 years of age
• Histologically confirmed adenocarcinoma of the breast ≥1.0 cm operable stage I-III
• Must have adequate organ function,
• Not receive systemic neoadjuvant therapy
• Be willing to provide tissue, blood, and stool samples for research study.
• Must not have taken any probiotics in the past 60 days prior to enrollment.

Exclusion Criteria:

• Patients with autoimmune disease, immune deficiency such as HIV, irritable bowel, known diverticulosis, and other serious GI conditions at treating physician's discretion will be excluded.