The study primarily aims at evaluating health-related quality of life after radiotherapy for prostate cancer, using modern hypofractionated radiotherapy schedules. Study design is a prospective observational cohort study. All patients give written informed consent and fill out online validated questionnaires before, during, and after radiotherapy (yearly) up to 5 years post-treatment.

Rationale: Patient-Reported Outcomes (PROs), such as health-related quality of life (HRQL), have achieved an important role in the evaluation of benefits and harms after cancer treatment, including radiotherapy for prostate cancer (PCa). In the past year, clinical radiotherapy protocols at the Erasmus MC have been changed for external beam radiotherapy (EBRT) as well as for brachytherapy (BT). In order to evaluate the current, changed, clinical practice, we will conduct a prospective cohort study, with the main purpose to assess HRQL for the current treatment options at the Erasmus MC.

Objective: To establish HRQL (start treatment - 5 years after treatment) in a prospective cohort of ≈600 patients with localized PCa treated with radiotherapy within in the period ≈ 1/3/2019 - 1/12/2023.

Main objective: to establish changes in HRQL levels (with respect to baseline) up to 5 year post-treatment, within each radiotherapy modality for prostate cancer patients, i.e. EBRT 60 Gy in 20 fractions, EBRT 42.7 Gy in 7 fractions, CyberKnife (stereotactic EBRT) 38 Gy in 4 fractions, BT 27 Gy in 2 fractions, postoperative EBRT (PORT) 72 Gy in 36 fractions, EBRT for LN+: 70 Gy (prostate)/52 Gy (lymph nodes) in 28 fractions.

Study design: Prospective observational cohort study. Study population: Patients with prostate cancer T1c-T4 referred for radiotherapy at the Erasmus MC as a primary treatment with curative intent or as first line adjuvant treatment after a prostatectomy.

Intervention: All interventions are according to applicable standard clinical procedures & protocols for localized prostate cancer of the Radiotherapy department.

Main study parameters/endpoints: HRQL scores of the EPIC (urinary domain, bowel domain), and the IIEF-5 (sexual function) score.

Nature and extent of the burden and risks associated with participation, benefit and group relatedness: There are no additional risks or benefits for patients that participate in the study. The additional burden is to fill out questionnaires at regular intervals.

Study patient recruitment period was from April 2019 to May 2025, enrolling about 695 eligible patients, mainly treated with UHF 7x6.1 Gy (n=240), MHF 20x3/3.1 Gy (n=210), PORT (n=85), and brachytherapy (n=65).

Inclusion Criteria:

• Clinically T1c-T4, N0 (or N+ in case of EBRT-LN+), M0 prostate cancer patient referred for radiotherapy.
• Willing and capable to fill out Dutch questionnaires on health-related items at a computer (online questionnaires).
• Signed written Informed Consent.

Exclusion Criteria:

• Previously radiation treatment in the pelvic region, for any reason.
• Diagnosed with other tumor in the past 12 months or known with tumor progression of another tumor.
• Postoperative radiotherapy with dose levels < 72 Gy.

Clinically T1c-T4, N0 (or N+ in case of EBRT-LN+), M0 prostate cancer patients referred for radiotherapy to the Erasmus Medical Center.

Datasets used for publications (in the future) will be made available upon request. Requests for taking part in meta-analyses initiated by other research groups will be considered after publication of the main endpoints.