Image-guided Focal Dose Escalation- Primary pc Treated With Primary External Beam Hypofract.Stereotactic rt

Overview

Technical advances in radiotherapy (RT) treatment planning and delivery have substantially changed RT concepts for primary prostate cancer (PCa) by (i) enabling a reduction of treatment time and by (ii) enabling a safe delivery of high RT doses. Several studies proposed a dose-response relationship for patients with primary prostate cancer (PCa) and especially in patients with high-risk features a dose escalation should lead to improved tumor control. In parallel to the improvements in RT techniques, diagnostic imaging techniques like multiparametric magnetic resonance imaging (mpMRI) and positron-emission tomography (PET) evolved and enable an accurate depiction of the intraprostatic tumor mass for the first time. The HypoFocal-SBRT study combines ultra-hypofractionated RT / stereotactic body RT (reduction of treatment time) with a focal RT dose escalation on intraprostatic tumor sides by applying state of the art diagnostic imaging and most modern RT concepts. This novel concept will be compared with moderate hypofractionated RT (MHRT), one option for the curative primary treatment of PCa, which has been proven by several prospective trials and is recommended and carried out worldwide. We suspect an increase in relapse-free survival (RFS) and we will also assess quality of life in order to detect potential changes.

Prostate cancer (PCa) is the most frequent diagnosed malignancy in male patients in Europe and radiation therapy (RT) is a main treatment option. Conventional RT for patients with primary PCa aims at delivering a homogeneous dose to the entire prostatic gland. However, recent studies proved that modern medical imaging is able to detect accurately the intraprostatic tumour mass (ITM). Consequently, RT concepts for PCa have an imminent need to be rectified in order to individualize the RT strategy by considering the individual tumor localization. In addition, the radiobiological characteristics of the major organs at risk, the rectum and urinary bladder / urethra, as well as of the PCa itself speak for clear advantages of hypofractionated radiation therapy. High-precision stereotactic body radiation therapy (SBRT) significantly shortens the duration of treatment, with clear implications for quality of life and socio-economic aspects. The aim of this prospective, randomized, multicenter phase III study is the personalization of RT for patients with primary PCa based on individual tumor geometry derived from modern imaging techniques (mpMRI and PSMA-PET/CT). In the experimental (arm A) simultaneous RT dose escalation to the ITM will be performed under strict adherence to the organs at risks' dose constraints by using SBRT (ultra-hypofractionated radiation therapy) in a shorter treatment time (5 fractions vs. 20 fractions). In the control arm (arm B) the entire prostatic gland will receive a homogeneous moderately hypofractionated RT according to the current guidelines. RFS after RT (calculated from randomization) will be assessed as the primary endpoint as well as toxicities and patient reported quality of life as secondary endpoints. For the patients in the experimental arm we expect a significant benefit in relapse free survival (from 80% to 90% at 5 years). The improvement in relapse free survival could increase the metastatic free survival, prostate cancer survival and overall survival in high risk PCa patients. Considering the epidemiological importance of the PCa these results could have a significant socio-economic impact. In parallel a translational research program will address the identification of novel biomarkers/bio-imaging-markers predictive for outcome after RT. Furthermore, involvement of patient representatives includes information about the studies status and contributes to patient empowerment. These aspects will facilitate the evolution from an individualized RT to a personalized RT.