- Specialty Pleural Mesothelioma
-
Mayo Clinic
Address:200 First St. SW
Rochester, MN 55905
Telephone: (507) 538-3270 - Procedure Radiation Therapy
Dr. William Breen
Radiation Oncologist
Dr. William Breen is a radiation oncologist who treats mesothelioma and other complex cancers at Mayo Clinic. He focuses on advanced radiation therapy techniques to help improve life expectancy while protecting healthy tissue. Learn more about Dr. Breen and get help connecting with him today.
or call (866) 608-8933
Overview
About Dr. William Breen
William Breen, M.D., is a board-certified radiation oncologist with extensive experience treating mesothelioma and other thoracic cancers.
He practices at Mayo Clinic Comprehensive Cancer Center in Rochester, Minnesota, where he works with a multidisciplinary team to support mesothelioma patients through diagnosis, treatment, and follow-up care.
As part of a comprehensive cancer center environment, he helps patients access advanced mesothelioma treatment options tailored to their needs.
Dr. Breen’s work also includes research, leading studies on how radiotherapy, proton therapy, and immunotherapy can improve outcomes while reducing treatment side effects.
Use our Free Doctor Match to see if Dr. Breen may be a fit for your mesothelioma treatment needs in Minnesota.
What Health Conditions Does Dr. William Breen Treat?
As a radiation oncologist, Dr. Breen treats a range of cancers and related conditions that may benefit from highly targeted radiation therapy.
His main areas of focus include:
- Pleural mesothelioma: A rare cancer that develops in the lining around the lungs after asbestos exposure
- Lung cancer: Cancer that begins in the lungs and may cause coughing, breathing problems, chest pain, or fatigue
- Thoracic cancers: Cancers located inside the chest cavity, including cancers near the lungs, esophagus, or chest wall
- Brain and central nervous system tumors: Cancers that affect the brain, spinal cord, or surrounding nerves
- Lymphoma: A cancer affecting the lymphatic system, which helps the body fight infection
Dr. Breen works closely with surgeons, medical oncologists, patient navigators, and patient advocates to help patients understand treatment options and next steps.
Dr. William Breen’s Approach to Mesothelioma Treatment
Dr. William Breen approaches mesothelioma treatment through advanced radiation oncology and multidisciplinary planning.
His treatment approach often includes:
- Proton therapy: An advanced option that may reduce radiation exposure to surrounding organs
- Radiation therapy: Designed to target cancer while sparing nearby healthy tissue
- Stereotactic body radiation therapy (SBRT): A highly targeted form of radiation delivered with precision over fewer treatment sessions
Dr. Breen’s work reflects a careful balance between treatment effectiveness and quality of life. He helps patients understand how radiotherapy may fit into larger treatment plans that can also involve surgery, chemotherapy, and palliative care.
Download our Free Checklist of Questions to Ask Your Doctor to help prepare for discussions about treatment with Dr. Breen and other specialists.
Dr. William Breen’s Medical Background
Dr. Breen completed his undergraduate education at Saint John’s University, where he earned a Bachelor of Arts in Biochemistry with a minor in Latin. His early academic background combined science-focused coursework with broader studies in language and the humanities.
He went on to attend Mayo Medical School, now known as Mayo Clinic Alix School of Medicine, in Rochester, Minnesota, where he earned his medical degree in 2017. During medical school, he developed a strong interest in oncology, advanced radiation techniques, and research involving complex cancers.
After earning his medical degree, Dr. Breen completed a transitional internship at Gundersen Lutheran Medical Center in 2018. He then returned to Mayo Clinic to complete his residency training in Radiation Oncology through the Mayo School of Graduate Medical Education, finishing residency in 2022. He then continued directly into clinical and research leadership roles at Mayo Clinic after residency.
Dr. Breen’s Work Experience
Dr. Breen has worked in several clinical, research, and leadership positions within Mayo Clinic’s Department of Radiation Oncology.
His professional roles have included:
- Associate Research Chair, Department of Radiation Oncology, Mayo Clinic
- Assistant Professor of Radiation Oncology, Mayo Clinic
- Chair, Mayo Enterprise CNS Radiation Oncology Disease Group
- Co-chair, Mayo Enterprise CNS Radiation Oncology Disease Group (2022-2025)
- Consultant in the Department of Radiation Oncology at Mayo Clinic
- Leadership roles in radiation oncology research committees and telemedicine initiatives
- Principal investigator on multiple cancer clinical trials
His years of experience across patient care, research, and education have helped establish him as a respected mesothelioma specialist and radiation oncologist.
Highlights of Dr. William Breen’s Medical Career
Dr. Breen is recognized for his work in radiation oncology, mesothelioma research, and thoracic cancer treatment at Mayo Clinic.
His career highlights include leadership roles in radiation oncology research, published studies involving immunotherapy and advanced radiation technologies, and patient awards recognizing his commitment to communication and quality care.
Awards and Accolades
Dr. Breen has earned honors at Mayo Clinic for the care and guidance he provides to people undergoing mesothelioma treatment.
His notable honors and awards include:
- 2024 Top Performer Patient Experience Award
- 2025 Top Performer Patient Experience Award
These awards reflect Dr. Breen’s commitment to helping patients feel informed, comfortable, and supported throughout mesothelioma treatment.
Professional Affiliations
Dr. Breen remains active in several professional organizations and research groups related to radiation oncology, neuro-oncology, lymphoma treatment, and cancer clinical trials.
His professional affiliations include:
- Alliance for Clinical Trials in Oncology
- American Radium Society Brain Malignancy Panel
- American Society for Radiation Oncology (ASTRO)
- Brain Tumor Core Committee, NRG Oncology
- International Lymphoma Radiation Oncology Group
- Mayo Clinic Radiation Oncology Research Committee
- Society of Neuro-Oncology
Through these affiliations, Dr. Breen collaborates with physicians and researchers studying newer radiation techniques, clinical trial therapies, and treatment strategies for mesothelioma and other complex cancers.
Dr. William Breen’s Work in Cancer Treatment & Clinical Trials
Dr. Breen’s research is closely connected to the care mesothelioma patients receive at Mayo Clinic. His work focuses on newer radiation techniques designed to target tumors more precisely while helping limit radiation exposure near the lungs, heart, and surrounding tissue.
He has served as principal investigator on clinical trials involving mesothelioma, including studies exploring how radiation and immunotherapy may work together to improve treatment response.
“The radiation helps the immunotherapy see the tumor a little bit better and do its job a little more.”
– Dr. William Breen, mesothelioma specialist
Dr. Breen has also researched advanced imaging methods that help doctors map mesothelioma tumors more accurately before treatment begins. For eligible patients, this research may provide access to newer therapies and clinical trials that aren’t widely available outside major cancer centers.
Use our Free Doctor Match to find out whether Dr. Breen’s newer radiation therapies for mesothelioma may be available to you.
Dr. William Breen’s Mesothelioma Research and Published Works
Dr. Breen has contributed to several research articles involving mesothelioma and lung cancer, with a focus on radiation oncology, treatment response, and patient outcomes.
Some of his published works include:
- Safety and Outcomes of Intensity-Modulated Proton Therapy in Patients with Non-Small-Cell Lung Cancer with Interstitial Lung Disease. Published in Lung Cancer, October 2025.
- Adjuvant Radiation Therapy for Pleural Mesothelioma after Extrapleural Pneumonectomy (EPP) or Pleurectomy and Decortication (P+D). Published in International Journal of Radiation Oncology, Biology, Physics, November 2020.
- How Accurate Is Clinical Staging for Malignant Pleural Mesothelioma? Presented as a conference paper, May 2020.
- Surgery for Mesothelioma After Radiation Therapy (SMART): A Single Institution Experience. Published in Frontiers in Oncology, March 2020.
His published research continues to contribute to discussions surrounding mesothelioma care, thoracic cancer treatment planning, and the evolving role of radiation therapy in complex cancer treatment.
Get in Touch With Dr. William Breen
A mesothelioma diagnosis can leave patients and families with difficult decisions about treatment, clinical trials, and what comes next. Trying to compare options and understand where radiation therapy fits into treatment can quickly become exhausting.
Dr. William Breen treats mesothelioma patients at Mayo Clinic using advanced radiation techniques and research-driven treatment approaches. His work in proton therapy, SBRT, and immunotherapy-related clinical trials gives patients access to specialized mesothelioma treatment and newer therapies being studied for this rare cancer.
At Mesothelioma Hope, we help patients and families connect with mesothelioma specialists, treatment centers, financial resources, and support services.
Call (866) 608-8933 or use our Free Doctor Match to connect with Dr. Breen and get started with mesothelioma treatment.
Mesothelioma Hope has no affiliation with and is not endorsed or sponsored by Dr. William Breen. Any contact information listed is for informational purposes only. You have the right to contact Dr. William Breen directly.
Written by:Jenna Tozzi, RNJenna Tozzi, RN, is the Chief Patient Care Advisor for Mesothelioma Hope. With more than 15 years of experience as an adult and pediatric oncology nurse navigator, Jenna provides exceptional guidance and support to cancer patients and their loved ones. Jenna has been featured in Oncology Nursing News and is a member of the Academy of Oncology Nurse & Patient Navigators & the American Nurses Association.
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