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J. Isabelle Choi, MD, FACRO

Director of Research, Clinical Director

Dr. Isabelle Choi is the Director of Research, Clinical Director, and a Research Associate Professor at the New York Proton Center. She is appointed to national and international leadership positions in both the proton therapy and conventional photon therapy communities. Dr. Choi is a Radiation Oncology Attending in the Department of Radiation Oncology at Memorial Sloan Kettering Cancer Center.


Prior to joining the New York Proton Center, Dr. Choi was the Clinical Director at the California Protons Cancer Therapy Center in San Diego, California, where she also served as the Associate Director of Clinical Research and the Chief of the Breast Cancer, Thoracic Oncology, and Gynecologic Services for the center. She was then appointed Assistant Professor at the University of Maryland School of Medicine and served as a clinical lead of the Maryland Proton Treatment Center.



Breast cancers

Gastrointestinal (GI) cancers

→ Ductal carcinoma in situ (DCIS)

Anal cancer

Rectal cancer

Esophageal cancer

Gynecological cancer

Recurrent cancer

Education and Board Certifications


Harvard University

Medical School

University of Texas Health Science Center School of Medicine


Kaiser Permanente Los Angeles Medical Center (Chief Resident)

Board Certifications

Radiation Oncology


Dr. Choi’s research focuses on improving outcomes, reducing toxicities and more effectively delivering radiotherapy for breast cancer and gastrointestinal malignancies. As NYPC’s Director of Research, she oversees 22 clinical trials across numerous types of cancers. She is the principal investigator of numerous clinical trials at NYPC, including:


– Phase II Protocol of Proton Therapy for Partial Breast Irradiation in Early-Stage Breast Cancer


– A Randomized Phase III Trial Evaluating the Role Of Axillary Lymph Node Dissection In Breast Cancer Patients (cT1-3 N1) Who Have Positive Sentinel Lymph Node Disease After Neoadjuvant Chemotherapy


– Phase III Randomized Trial of Proton Beam Therapy (PBT) Versus Intensity Modulated Photon Radiotherapy (IMRT) for the Treatment of Esophageal Cancer


– Prospective Evaluation of Pencil Beam Scanning Proton Therapy for Previously Irradiated Tumors.

Leadership Appointments

Among her select national leadership appointments, Dr. Choi is Chair of the Proton Collaborative Group (PCG) Publications Committee, Chair of the PCG Breast Subcommittee, Chair of the National Association of Proton Therapy’s Physician Advisory Committee, and President of the Korean American Society of Radiation Oncology.

Dr. Choi utilizes evidence-based treatment paradigms and the most cutting-edge therapeutic techniques available to produce the best clinical outcomes possible. She considers short- and long-term quality of life and the goals of her patients and uses shared decision-making with them and their caregivers to develop an optimal and individualized plan of care that provides the level of care she'd wish to be delivered to her own loved ones.
Latest Blog
Dr. J. Isabelle Choi Named to Crain's New York Business ‘40 Under 40’ List
Dr. J. Isabelle Choi Elected a Fellow of the American College of Radiation Oncology (FACRO)
The Impact of Proton Therapy Research at NYPC

How can we help?

Want to find out if proton therapy might be a good fit for you or your patient? Call us at 833-NYPROTON (833-697-7686) or fill out the appropriate form below.