Cancer is a disease that changes over time. When cancer changes, a treatment that worked before might start to become less effective. Hormone tablets are approved in Australia to treat advanced prostate cancer, however, even if these drugs are helpful their effectiveness usually diminishes over time. The ANZadapt trial is testing a new idea to try to slow down the changes in cancer by giving treatment for just long enough to control the cancer, and then pausing the treatment if the cancer is controlled. If the cancer starts to grow again, the treatment is started again to try to control the cancer again. This idea is called ‘adaptive therapy’ as the treatment is adapted for each person. Adaptive therapy may slow how cancer changes and keep treatment useful for as long as possible when a treatment can control a cancer, but can't cure the cancer. The ANZadapt aims to find out if this pause/restart strategy is better than taking hormone tablets every day continuously.