The aim of this phase II study is to determine the early multiparametric magnetic resonance imaging response of the dominant intraprostatic lesion and correlate these findings with prostate specific antigen response in patients with intermediate to (very) high risk localized prostate cancer treated with online adaptive stereotactic radiotherapy without intraprostatic fiducial markers.
Background: Stereotactic body radiotherapy (SBRT) is an established standard of care treatment for localized prostate cancer. Recent pathological studies suggest the presence of a dominant intraprostatic lesion (DIL) within the prostate, which serve as a central driver of tumor aggressiveness and recurrence after treatment. Prostate-specific antigen (PSA) monitoring is the cornerstone of follow-up, though time to PSA nadir after SBRT can extend to 3 years. Methods: This phase II observational study aims to evaluate the correlation between PSA response and early multiparametric magnetic resonance imaging (mpMRI) changes of the DIL(s) at 6- or 9-months following online adaptive SBRT for intermediate to (very) high risk localized prostate cancer. The primary outcome is the achievement of local control as assessed by mpMRI at 6 months post-SBRT or, if necessary, at 9 months post-SBRT (in case of image non complete response at 6 months). A complete imaging response is defined as the disappearance of all morphological and functional mpMRI changes of PIRADS (Prostate Imaging Reporting and Data System) ≥3 lesion(s) correlating with Gleason ≥7a pathology. No confirmatory biopsies will be conducted. The required sample size for this study will be 28 patients, assuming a complete response rate of 80% at 6 months, targeting an acceptable margin of error with 95% confidence, and a margin of error of 15%.
Study Type
OBSERVATIONAL
Enrollment
28
University Hospital Zurich
Zurich, Switzerland
Multiparametric magnetic resonance imaging local control of the dominant intraprostatic lesion
To study multiparametric magnetic resonance imaging (mpMRI) local control of Prostate Imaging Reporting and Data System (PIRADS) ≥3 lesion(s) after SBRT. An image complete response is defined as disappearance of all morphological and functional PIRADS ≥3 lesion(s) correlating with Gleason ≥7a pathology in mpMRI.
Time frame: 6 months after SBRT. In cases with image non-complete response at 6 months, 3 months later (in total 9 months after SBRT) an additional mpMRI will be performed.
Correlation of early prostate-specific antigen response with early multiparametric magnetic resonance imaging changes
To correlate early prostate-specific antigen response with early multiparametric magnetic resonance imaging changes of the PIRADS ≥3 lesion(s) correlating with Gleason ≥7a pathology
Time frame: 6 months after SBRT. In cases with image non-complete response at 6 months, 3 months later (in total 9 months after SBRT) an additional mpMRI will be performed.
Correlation of late prostate-specific antigen response with early multiparametric magnetic resonance imaging changes
To correlate late prostate-specific antigen response with early multiparametric magnetic resonance imaging changes of the PIRADS ≥3 lesion(s) correlating with Gleason ≥7a pathology
Time frame: Yearly (up to 5 years post SBRT)
Correlation of genitourinary and gastrointestinal toxicity with early multiparametric magnetic resonance imaging changes
Correlating genitourinary and/or gastrointestinal toxicity (according to common terminology criteria for adverse events \[CTCAE\] version 5.0) with structural and/or functional changes of the prostate and/or surrounding organs on early multiparametric magnetic resonance imaging
Time frame: 6 months after SBRT. In cases with image non-complete response at 6 months, 3 months later (in total 9 months after SBRT) an additional mpMRI will be performed.
Correlation of prostate quality of life with early multiparametric magnetic resonance imaging changes
Quality of life (according to EPIC-26) and relation to early structural and/or functional changes of the prostate and/or surrounding organs on multiparametric magnetic resonance imaging
Time frame: 6 months after SBRT. In cases with image non-complete response at 6 months, 3 months later (in total 9 months after SBRT) an additional mpMRI will be performed.
To evaluate prostate volume change during and after adaptive prostate SBRT and to correlate to treatment toxicity.
To evaluate prostate volume change intra-treatment and after adaptive prostate SBRT and to correlate to treatment toxicity.
Time frame: Intra-treatment (within 1 week before the last fraction of SBRT) and 6 months after SBRT. In cases with image non-complete response at 6 months, 3 months later (in total 9 months after SBRT) an additional mpMRI will be performed.
Exploratory image analysis
Quantitative imaging features will be used to predict outcome and side effects on the different images.
Time frame: 6 months after SBRT. In cases with image non-complete response at 6 months, 3 months later (in total 9 months after SBRT) an additional mpMRI will be performed.
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