New Study Findings: Probiotics May Help Boost Breast Cancer Therapy

Despite the prevalence of breast cancer, many cases are unrelated to known risk factors. Furthermore, not all individuals with genetic predisposition or exposure to documented environmental factors develop the disease.

Multiple recent evidence suggests that the gut microbiome plays a significant role in immunity and other essential host processes and that microbial dysbiosis contributes to disease states, including malignancy. 

About two-thirds of breast cancer tumors are sensitive to hormones like estrogen and progesterone, indicating that the tumor’s cells have receptors that use hormones as fuel to grow. 

Research indicates that the breast’s unique microbiome changes with diet or the presence of tumors.

Lactobacillus Decrease Tumor Cells Proliferation

In a study by researchers at Wake Forest University in Winston-Salem, NC, the team discovered that probiotics might amplify the anticancer effect of the drug tamoxifen, a commonly used medication for breast cancer that consists of an endocrine targeted therapy.

For the study, the team used a mice model. During the study, the mice were given a Mediterranean-like or a Western-like, high-fat diet, and given tamoxifen for 3 months. 

The researchers found that the mice that were taking tamoxifen had elevated levels of Lactobacillus in their breast tissue. This is a gram-negative bacteria that has been found to have anti-inflammatory properties. 

The team then injected Lactobacillus directly into the mammary glands of mice that had breast tumors and found that they had decreased tumor formation and proliferation of tumor cells. 

During the third phase of the study, the same team analyzed tissue from estrogen receptor + (ER+) breast tumors from women receiving neoadjuvant endocrine-targeted therapy. The team found similar results, with women with elevated levels of gram-positive bacteria in their tumors showing lower levels of cancer cell growth. 


Tzeng, A., Sangwan, N., Jia, M. et al. Human breast microbiome correlates with prognostic features and immunological signatures in breast cancer. Genome Med 13, 60 (2021).  

Jeanna D. Smiley. (2022, Jun 23). Probiotics may give tamoxifen a boost in breast cancer treatment. Medical News Today. Retrieved from:

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