Hi @marko1, you'll notice that I moved your message to the Prostate Cancer group. I did this so you can meet others talking about prostate cancer and treatment. You ask a very good question. Why can't we just kill the cancer cells and not destroy the good cells? More and more therapies are being studied to do just that. These are called targeted therapies that target the cancer cells specifically.

Click this link and scroll down to the section called "The latest treatment options". There you will see a list of radiation therapy techniques used by Mayo Clinic. Mayo Clinic radiation oncologists are experts in planning treatment that targets prostate cancer cells and spares as much nearby healthy tissue as possible.
https://www.mayoclinic.org/diseases-conditions/prostate-cancer/care-at-mayo-clinic/mac-20353097
Have you asked your oncologist about clinical trials that you may be eligible for? Have you been diagnosed with prostate cancer?