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Heather L. McArthur, MD, MPH

Medical Director, Breast Oncology
Cedars-Sinai Medical Center
Los Angeles, California

Current Research

  • Seeking to improve treatments and outcomes for patients with metastatic breast cancer.

  • A clinical trial is planned to test the combination of immune modulation plus a short course of radiation in breast cancer patients.

  • These studies may lead to combination strategies to reduce resistance to immunotherapy and improve patient outcomes.

Although treatment advances over the past two decades have significantly improved outcomes for women diagnosed with operable early stage breast cancer, up to one-third will experience a distant recurrence and ultimately die of metastatic breast cancer.

A growing body of evidence indicates that breast cancer is a heterogeneous disease and that responses to therapy are influenced by each tumor's unique biology and gene mutation profile. Dr. McArthur believes that immune-based strategies that stimulate the immune system to recognize specific features of a tumor may improve patient outcomes.

Studies have shown that destruction of tumor tissue by cryoablation (freezing) or radiation activates critical tumor-specific immune cells. Immune-based therapies called checkpoint inhibitors (ipilimumab, tremelimumab and pembrolizumab are examples) have improved patient outcomes in many advanced cancers and synergize with cryoablation and radiation to block tumor growth in laboratory models.

Dr. McArthur has conducted clinical studies combining checkpoint inhibitors with radiation or cryoablation in both early and advanced breast cancer with encouraging results.

In the upcoming year, Dr. McArthur and her team will build on these unique experiences by performing pre-operative immune modulation plus a short course of radiation in women with breast cancers of any tumor subtype for whom post-operative radiation is planned.

The team believes that by combining immune modulation with radiation before (instead of after) surgery, the biology of an individual patient’s tumor and her immune system can be exploited to confer long-term immunity, and ultimately a cure.


Heather McArthur, MD, MPH is a medical oncologist with a clinical practice dedicated to the care of patients with breast cancer. Her research activities are focused on innovations in the diagnosis and treatment of breast cancer, with a particular interest in novel immune therapy strategies. She is currently evaluating the impact of tumor destruction with freezing (cryoablation) in combination with immune stimulation for the treatment of women with early stage breast cancer. It is hoped that by augmenting one's immune response to the unique biologic features of one's tumor, that an affected individual may develop long-term immunity against their tumor, and thus, be cured.

Dr. McArthur completed formal medical oncology training at the University of British Columbia. There, she was awarded the highly competitive Canadian Association of Medical Oncology/Canadian Institute for Health Research R&D Fellowship which funded her advanced clinical research fellowship at MSKCC. She has a Master’s in Public Health from Harvard. She has presented her research at the ASCO Annual Meeting and the San Antonio Breast Cancer Symposium, and has served on the Conquer Cancer Foundation of ASCO YIA/CDA Grants Selection Committee, the ASCO Breast Cancer Symposium Program Committee, and a NCI Breast Cancer Steering Committee Working Group. She has been a reviewer for several clinical journals including the New England Journal of Medicine, Nature Clinical Practice Oncology, the Journal of Clinical Oncology, Cancer, and Clinical Breast Cancer and has written more than 50 articles, review articles, invited commentaries, and book chapters on breast cancer.

BCRF Investigator Since


Donor Recognition

The ULTA Beauty Award

Area(s) of Focus