Ralph P. Ermoian, MD

Ralph P. Ermoian, MD
Top Doctor icon

Ralph P. Ermoian, MD

  • Physician, Fred Hutch
  • Associate Professor, Department of Radiation Oncology; Adjunct Professor, Department of Pediatrics, University of Washington School of Medicine
  • Physician, Seattle Children's

Radiation Oncology

“One of the things I enjoy most about my specialty are the close relationships I develop with patients and families as well as my professional practice partners. It’s a team effort that results in the best outcomes.”

— Dr. Ermoian

Tell us about an interaction with a patient that has had a significant impact on you.

I once treated a preteen patient who was an extraordinary student. Unfortunately, she had developed a brain tumor that required a significant amount of radiation therapy. While radiation can be a very effective form of treatment, there are several potential long-term side effects to consider. Before moving forward, I had a long discussion with this patient and her family about how radiation therapy could impact the sharpness of her thinking — and ultimately her academic ambitions. After she completed her course of treatment, her family frequently wrote to me to share how well she was doing. Year after year, they would tell me about how she was still at the top of her class and eventually how she got accepted to an outstanding college. It was so exciting to hear that she was thriving and pursuing her career goals. One of the things I enjoy most about my specialty are the close relationships I develop with patients and families as well as my professional practice partners. It’s a team effort that results in the best outcomes.

What would you like patients and families to know about working with you?

I often tell patients and families that I’m going to expect the best, both in terms of how a tumor will respond to radiation therapy and how a patient will feel while receiving this treatment. Yet, while expecting the best, I also remain vigilant about evaluating for side effects and monitoring for cancer recurrence. My goal is to provide care that’s compassionate, detail-oriented and centered on your medical needs and goals.

Provider Background

Specialty: Radiation Oncology

Pediatric malignancies, brain tumors, blood-related cancers requiring stem cell transplantation
I am a board-certified radiation oncologist who specializes in treating children with brain tumors, sarcomas and other forms of cancer. I also provide radiation therapy for adult and pediatric patients who are preparing for a stem cell transplant as well as those seeking palliative treatment (relief for tumor-related symptoms).

My research is focused on examining the outcomes of pediatric patients who receive radiation therapy. I also collaborate with other physicians to develop interventions that minimize the need for very young patients to receive anesthesia during radiation therapy, which can be very disruptive for families. Other research interests include improving the safety of radiation therapy and addressing issues of equity and access to this treatment.

Diseases Treated

Brain Tumors

Langerhans' Cell Histiocytosis


Wilms Tumor



Education, Experience and Certifications

Undergraduate Degree
Stanford University

Medical Degree
University of California, San Francisco

University of California, San Francisco, Pediatrics; University of Washington, Radiation Oncology

University of California, San Francisco

Board Certification
Pediatrics, 2007; Radiation Oncology, 2012, American Board of Radiology

Internship, Children's Hospital Boston; Teaching Appointment, University of California, Berkeley

Seattle Met's 2020 Top Doctors Award
Dr. Ermoian has been recognized as a Top Doctor in Seattle Met's annual survey.


All news
The challenges of cancer caregiving As the population ages, more family caregivers are being pressed into service November 1, 2023

Clinical Trials

We make promising new treatments available to you through studies called clinical trials led by Fred Hutch doctors. Many of these trials at Fred Hutch have led to FDA-approved treatments and have improved standards of care globally. Together, you and your doctor can decide if a study is right for you.

Your Care Team

At Fred Hutch, you receive care from a team of providers with extensive experience in your disease. Your team includes doctors, a patient care coordinator, a registered nurse, an advanced practice provider and others, based on your needs. You also have access to experts like nutritionists, social workers, acupuncturists, psychiatrists and more who specialize in supporting people with cancer or blood disorders.


Fred Hutch accepts most national private health insurance plans as well as Medicare. We also accept Medicaid for people from Washington, Alaska, Montana and Idaho. We are working to ensure that everyone, no matter what their financial situation, has access to the care they need.

For the Media

The Media Relations team at Fred Hutch is available to assist members of the news media who would like to arrange interviews with providers.

Email media@fredhutch.org or call 206.667.2210