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Leslie L. Montgomery, MD, FACS

Chief, Division of Breast Surgery, Hackensack University Medical Center
Co-Chief, Breast Service, John Theurer Cancer Center
Hackensack University Medical Center
Hackensack, New Jersey

Current Research

  • Seeking to identify innovative approaches to improve response to therapies for triple negative breast cancer.

  • A clinical study is conducted to measure changes in the gut microbiome before, during and after treatment in patients with triple negative breast cancer to identify biomarkers that can predict response to therapy.

  • This study may identify new biomarkers that can inform future studies.

The bacteria that inhabit our gut play vital roles in health and diseases, including cancer. Scientists are studying the gut microbiome to understand its role in cancer development, as well as how the cancer responds to therapy. Triple negative breast cancer (TNBC) is an aggressive disease treated primarily by chemotherapy, but many patients do not respond to the treatment. Drs. Montgomery and Feinman are studying changes in the gut microbiome after chemotherapy treatment in patients newly diagnosed with TNBC to identify markers than may predict how patients will respond to chemotherapy.

Full Research Summary

Triple negative breast cancer (TNBC) is an aggressive heterogeneous disease accounting for 15-20 percent of all breast cancers. Although significant progress has been made in our understanding of the disease, there remains no targeted therapy and only 30 percent of TNBC patients respond to neoadjuvant (pre-surgery) chemotherapy. 

Drs. Montgomery and Feinman are conducting studies prompted by the recent discovery that the gut microbiome, consisting of tens of trillions of bacteria, contributes to the variability in immune response to cancer therapies. They hope to determine whether distinct gut microbial communities increase the efficacy of chemotherapies by re-activating the immune system to eradicate TNBC tumor cells. 

In their BCRF-supported research, Drs. Montgomery and Feinman will correlate changes in the composition of the gut microbiome with anti-tumor immune response in newly diagnosed TNBC patients before, during, and after standard neoadjuvant chemotherapy. 

Preliminary results of patient stool samples suggest that loss of bacterial diversity and alterations in the composition of the gut microbiome are primarily associated with the use of anthracyline-based chemotherapy. Microbiome diversity was restored after taxane-based chemotherapy. 

The researchers hope to identify novel biomarkers within the microbiome that can predict response to chemotherapy. Ultimately, they aim to find clues of how to optimize therapeutic strategies to improve outcomes for patients with TNBC.


Dr. Leslie L. Montgomery is a board-certified surgical oncologist specializing in breast cancer. She is Chief of the Division of Breast Surgery at Hackensack University Medical Center and the Co-Director of the Breast Service at John Theurer Cancer Center. She was formally an attending breast surgeon at Memorial Sloan Kettering Cancer Center for more than 11 years, where she served as Director of the Special Surveillance Breast Program and the Director of the Breast Surgical Oncology Fellowship Program. From 2009 through 2015, Dr. Montgomery was the Chief of the Division of Breast Surgery at Montefiore Medical Center and the Director of Breast Services at the Montefiore Einstein Center for Cancer Care.

Dr. Montgomery received her undergraduate degree at Stanford University and earned her medical degree at the University of California,  San Francisco. After her residency in general surgery at the New York Hospital/Cornell Medical Center, she completed research fellowships at the Brigham and Women’s Hospital in Boston, Massachusetts and at Memorial Sloan Kettering Cancer Center.

Her research interests include preoperative therapy trials to reduce the burden of disease in the breast and axillary nodes to minimize surgical intervention.

Leslie L. Montgomery

BCRF Investigator Since


Donor Recognition

The ANN INC. Award (a division of ascena retail group inc.)

Area(s) of Focus