When I had radiotherapy 6 years ago in the U.K. for Prostate Cancer I took part in a trial called PACE where you only had 5 sessions of radiotherapy over a period of 2 weeks, initially it was 1 week but they reverted to 2 weeks.with no hormone treatment. Prior to that it was 20 sessions, I don’t know how long for though but you also had hormone treatment. I believe now the NHS are going to adopt this method as it was deemed a success,
https://www.royalmarsden.nhs.uk/news-and-events/news/higher-doses-radiotherapy-cuts-treatment-time-75-localised-prostate-cancer