Dr Sean Brennan

Radiation Oncologist
Become a Patient

Dr Sean Brennan is dedicated to improving access to cancer care in rural and regional communities. His warm and engaging manner fosters strong and meaningful connections with both his patients and their loved ones.


Dr Sean Brennan is a senior radiation oncologist at Icon Cancer Centre in Mackay. Born in South Africa, Dr Brennan obtained a Bachelor of Medicine, Bachelor of Surgery (MBChB) at the University of Zimbabwe and undertook his specialist oncology training at Groote Schuur Hospital in Cape Town, South Africa. He gained further research experience and specialist expertise through positions at GVI Oncology (now Cancercare) and Eli Lilly Pharmaceuticals. Dr Brennan holds dual fellowships with the Faculty of Radiologists (Therapeutic) of South Africa and Royal Australian and New Zealand College of Radiologists (RANZCR).

Relocating to Australia in 2009, Dr Brennan was appointed as a senior radiation oncology staff specialist at Townsville Hospital. During his tenure in North Queensland, he made a significant contribution to the expansion of rural and regional oncology services. Dr Brennan held appointments as Director of Training at Townsville Hospital and Examiner and Honorary Lecturer at James Cook University. He has also worked as a senior radiation oncologist at South West Health Campus in Bunbury, Western Australia and in Central Queensland.

With a passion for specialist education, quality improvement and governance, Dr Brennan is actively involved in the teaching and mentoring of medical students and radiation oncology trainees. He has held numerous positions at RANZCR, including Phase II Examiner, Chief Examiner, Chief Censor and Chair of the Radiation Oncology Education and Training Committee. In 2023, Dr Brennan was awarded the RANZCR Roentgen Medal in recognition of his significant contribution to the profession. He has published and co-authored research articles and book chapters and has been an invited speaker at local and national conferences to present on the importance of telemedicine for rural cancer care in Queensland.

His clinical experience covers a broad range of general oncology, with a special interest in breast cancer, gastrointestinal cancer, lung cancer, skin cancer and brain and spinal (CNS) tumours.

Affiliations & Memberships

  • Royal Australian and New Zealand College of Radiologists (RANZCR)
  • European Society for Radiotherapy and Oncology (ESTRO)
  • Trans Tasman Radiation Oncology Group (TROG)
  • International Stereotactic Radiosurgery Society (ISRS)
  • Cooperative Trials Group for Neuro-Oncology (COGNO)

Special Interests

Dr Sean Brennan accepts referrals for all tumour types, with a special clinical interest in:
  • Brain and spine (CNS) cancer
  • Breast cancer
  • Gastrointestinal cancer
  • Lung cancer
  • Skin cancer

Icon Locations

Mackay View centre