Prostate cancer is the second most commonly diagnosed cancer among men and the second most common cause of death from cancer in men, yet many prostate cancers are not fatal and some autopsy series have demonstrated up to 50% or more silent prostate cancers in men over the age of 70 years.

Cancer is responsible for over 40,000 deaths annually in Australia and has traditionally been managed by modalities including surgery, radiotherapy and chemotherapy. In 1992, Tasuku Honjo's discovery of checkpoint proteins on tumour cells led to the birth of immunotherapy which has revolutionised the treatment of many cancers including bladder and kidney cancer, head and neck cancer, melanoma, non-small cell lung cancer and Hodgkin's lymphoma.