Since 2004, over 20 new proton beam centers, a type of radiation primarily identified as being effective in treating pediatric cancers, have been built in the USA. In this interview, Anthony Zietman, MD, from the Massachusetts General Hospital, Boston, MA, discusses how PSA testing and the increase in the number of men diagnosed with prostate cancer contributed to this. Dr Zietman highlights how the financial model in the USA is seeing this market quickly declining again. However, the UK has recently emerged with plans for two proton beam centers, which could provide the required evidence for the use of the treatment in non-pediatric cancer. This interview was recorded at the 2017 National Cancer Research Institute (NCRI) Conference, held in Liverpool, UK.