Protons vs. Photons for High-risk Prostate Cancer

The purpose of this study is to assess late gastro-intestinal side-effects comparing proton therapy to photon therapy in high-risk prostate cancer patients receiving whole pelvic irradiation.

Inclusion Criteria: * Histologically verified localized/locally advanced prostate cancer T1-3bN0-1M0 (TNM 8th edition). A clinical T4 is allowed if it is because of invasion into the bladder neck. * Adenocarcinoma (mixed histology allowed as long as the adenocarcinoma component comprise more than 50%) * Indication for elective lymph node irradiation * PSA \< 100 ng/mL * Age ≥18 years * Performance status 0-1 * Life expectancy ≥ 10 years * Able to understand and comply with the treatment protocol * No evidence of inflammatory bowel disease Ability to adhere to procedures for study and follow-up * Signed informed consent to participate in the study Exclusion Criteria: * No previous treatment for prostate cancer * Hip-prostheses * Other metal devices in the pelvic region (except fiducials) * Previous major abdominal/rectal surgery * Any other malignancy the last five years except for basal or squamous cell skin cancer * Unable to understand patient information or comply with treatment and safety instructions * Unable to read and understand patient information due to cognitive disabilities or language (Danish).