Professor Zalcberg has held the positions of Director of Cancer Services at Austin Health, Director of the Division of Cancer Medicine as well as Chief Medical Officer at the Peter MacCallum Cancer Centre, followed by his ongoing appointment as Professor of Cancer Research in the School of Public Health and Preventative Medicine in the Faculty of Medicine, Nursing and Health Sciences at Monash University (now Emeritus). He also holds an ongoing appointment as a Professorial Fellow in the Department of Medicine, Faculty of Medicine, University of Melbourne.
After obtaining a Bachelor of Medicine and Surgery from the University of Melbourne and a PhD in cancer immunology, he served as Director of Medical Oncology at the Heidelberg Repatriation Hospital and Director of Cancer Services at the Austin and Repatriation Medical Centre.
A co-founder of the Lorne Cancer Conference and Australasian Gastrointestinal Trials Group (AGITG), Professor Zalcberg held Board positions for AGITG (Chair), Cancer Trials Australia, Cancer Drugs Alliance (Co-Chair) and the Australian Clinical Trials Alliance (Chair). His prior board appointments include Progen Industries, New South Wales Cancer Institute, Clinical Oncological Society of Australia (President) and Consultative Council of the Victorian Cancer Agency.
In addition to his current appointment to the Board of ICON, he holds Board appointments on PRAXIS Australia, All.Can Australia and privately held Lipotech. He has also recently been appointed to the Advisory Council of Cancer Australia
In recognition of his substantial service to cancer research and clinical practice, Professor Zalcberg was honoured with a Medal of the Order of Australia Award (OAM) in 2007, and the 2011 Cancer Achievement Award from the Medical Oncology Group of Australia. In 2014 he was awarded the Tom Reeve Award for Outstanding Contributions to Cancer Care (awarded by the Clinical Oncology Society of Australia – COSA) and in the same year was honoured by the establishment of the eponymous award – the “John Zalcberg OAM Award for Excellence in Australasian Gastrointestinal Trials Group (AGITG) Research”; to be awarded annually by the AGITG. In 2016 he was appointed to the inaugural Tony Charlton Chair of Oncology, Alfred Health and Monash University and in 2018 received the Australian Red Cross Distinguished Service Award.
In 2023, Prof Zalcberg was appointed Officer of the Order of Australia (AO) for distinguished service to oncology as a clinician-researcher, and as an advocate for those living with cancer.