Surgeons look back and see the expectations of their predecessors exceeded, and obstacles to progress once thought to be insurmountable, bypassed as a matter of routine. But in cancer surgery there have been some notable reversals. Selection of only the most favourable cases and the need to accompany operations with chemotherapy and radiotherapy must raise doubts about how effective surgery itself is in controlling cancer. In this lecture, to mark World Cancer Day, Professor Treasure will describe research findings and changes in practice that indicate that the limits of cancer surgery may have already been overstepped. He poses the question: when our present day efforts become history, how will cancer surgery be judged by future generations?