Brian Deegan

Brian Deegan

Radiation Oncology
Languages Spoken


Brian J. Deegan, MD, is board-certified in radiation oncology and practices at Cancer Specialists of North Florida's (CSNF) Fleming Island and St. Augustine locations. After receiving his Bachelor of Arts in chemistry and biology from Luther College, he enrolled in a joint-degree program at the University of Miami. There, he received his Doctor of Philosophy in Cancer Biology and his Doctor of Medicine.

Dr. Deegan completed his residency training at the University of Texas, MD Anderson Cancer Center before joining CSNF’s growing radiation oncology department. Putting a focus on his patient’s personal values while caring for them allows him to further build that trust. He counts it a tremendous privilege to take care of patients and their families during a difficult period in their life. Dr. Deegan appreciates that responsibility and opportunity to earn their trust during their care.

When not in the office, Dr. Deegan enjoys traveling, watching sports, listening to music, and enjoying all of the outdoor activities North Florida has to offer with his wife and kids.



  • University OF MIAMI


  • University of Texas MD Anderson Cancer Center Program


  • University of Texas Health & Science Center.


Hospital Affiliations

  • Ascension St. Vincent's Clay County Hospital
  • Ascension St. Vincent's Riverside Hospital
  • Ascension St. Vincent's Southside Hospital
Professional Statement
I aim to get to know my patients and find out what is important to them before explaining their treatment course.
- Brian Deegan


Brian Deegan offers services at multiple Florida locations. Contact your preferred location to book an appointment.
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(904) 825-4500
Why Ascension
Ascension doctors are committed to getting to know you. They take time for real back-and-forth conversations with you so they can understand all aspects of you and your life. Because great care starts with seeing your whole picture.