Background: Three developments have each been shown to improve or simplify radiotherapy for prostate cancer: moderate hypofractionation, a focal boost to the dominant intraprostatic lesion, and elective pelvic lymph node irradiation in high-risk disease. Long-term data on combining all three in one protocol are lacking. A previous institutional phase II study (2007-2009) used a hypofractionated simultaneous integrated boost with uniform dose to the prostate and an elective pelvic field.
Design: Prospective, single-arm study at Haukeland University Hospital. Patients with high-risk prostate cancer, including clinically node-positive disease, were included from February 2014 to June 2017. For analysis, patients were grouped as high risk, very high risk, and node-positive.
Treatment: Image-guided IMRT in 25 fractions with a simultaneous integrated boost of 2.9 Gy per fraction (72.5 Gy) to the MRI-defined tumour, 2.4 Gy per fraction (60 Gy) to the uninvolved prostate and seminal vesicles, and 2.0 Gy per fraction (50 Gy) to the elective pelvic lymph nodes in all patients, with a simultaneous boost of 2.4 Gy per fraction (60 Gy) to involved lymph nodes in node-positive patients. Androgen deprivation therapy was planned for 18 months.
Follow-up: Patients were followed with PSA measurements and clinical examinations every 6 months for 5 years and annually thereafter. The protocol did not specify an end of follow-up; data collection was closed on 1 October 2025, and outcomes are reported up to 10 years. Endpoints are listed under Outcome Measures. Toxicity was physician-reported.
Registration: The study was approved by the Regional Committee for Medical and Health Research Ethics (2012/1863) before inclusion started. It was registered at ClinicalTrials.gov retrospectively, after completion of follow-up; this record reflects the ethics-approved protocol.
