Richard Cassidy

Richard Cassidy

Radiation Oncology
Languages Spoken


Richard J. Cassidy III, MD, is a board-certified radiation oncologist who practices at Cancer Specialists of North Florida's (CSNF) Fleming Island and Southpoint locations. Raised in North Florida, Dr. Cassidy received his medical degree from the University of Florida, where he was in the Junior Honors Medical Program and received Alpha Omega Alpha honors. He completed his radiation oncology training at Winship Cancer Institute of Emory University in Atlanta, Georgia, where he was chief resident.

Like many others, Dr. Cassidy has had personal experiences with cancer; both of his grandfathers lost their battles when he was young, and his grandmother lost hers soon after he finished medical school. These losses sharpened his interest and focus in improving oncology care. He believes that it's important to consider someone’s personal beliefs, wishes, and goals when providing care. Dr. Cassidy involves patients in their treatment plan, because cancer care is more than just addressing the medical condition — it involves the whole patient and their personal situation.

As someone who grew up playing sports, Dr. Cassidy believes that complex cancer care is a "team sport." He enjoys working closely with other physicians, nurses, pharmacists, and all of the medical staff needed for excellent patient care. “This cooperation makes for a close-knit atmosphere, which ultimately benefits patients and their families," he said.

When not at work, Dr. Cassidy enjoys spending time with his wife, their sons, and their families who are all located in the Jacksonville area. When he’s not chasing his toddler around, he still finds time to struggle at playing basketball and golf, as well as being a slightly over-the-top fan of Florida Gator sports.



  • University of Florida


  • Emory University School of Medicine


  • Emory University School of Medicine


Hospital Affiliations

  • Ascension St. Vincent's Clay County Hospital
  • Ascension St. Vincent's Riverside Hospital
  • Ascension St. Vincent's Southside Hospital
  • Ascension St. Vincent's St Johns County Hospital


  • The American Board of Radiology - Radiation Oncology
Professional Statement
It is an honor to serve my community and to directly give back to my hometown gives me extreme pride.
- Richard Cassidy


Richard Cassidy offers services at multiple Florida locations. Contact your preferred location to book an appointment.
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.