An impact of pelvic magnetic resonance imaging to radiotherapy volume definition in patients with intermediate- and high-risk prostate cancer: A Population based study
演題番号 : P25-10
1:Soroka University Medical Center, Israel・Department of Oncology・Onco - Urology Service、2:Meir Medical Center・Department of Oncology・Onco - Urology Service
This is a retrospective study to evaluate an influence of pelvic MRI (PMRI) to delineation of clinical target volume (CTV) for radiotherapy (RT) of intermediate- and high-risk prostate cancer.
Medical records of patients with intermediate and high-risk prostate cancer treated with intensity-modulated RT (IMRT) were examined retrospectively. Risk group was defined using NCCN criteria. PMRI reports were reviewed and risk group was re-defined in regards of T- and N-stage. CTVs for IMRT treatment plans were contoured applying PMRI. Extra-capsular extension (ECE) and seminal vesicles invasion (SVI) were included to high-dose CTV. Regional pelvic lymph nodes (RPLN) considered pathological by PMRI were included to separate CTV to receive RT dose higher than unaffected RPLN stations.
Between 2009 and 2013, 169 patients with intermediate and high-risk prostate cancer underwent PMRI at around 1 month before commencing IMRT. Initially, 89 patients were affiliated to intermediate-risk and 80 to high-risk group. In general, PTV-changes based on PMRI data required in 61 patients (36%). Thirty seven of 89 intermediate-risk patients (42%) were switched to high-risk group, necessitating irradiation of PLN. ECE and SVI were included to high-dose CTV in 64 (38%) and 29 patients (17%) respectively. PLN were thought pathological in 10 patients (6%), which justified contouring of a separate CTV for dose escalation.
In our series PMRI-scans had a significant impact on RT target coverage decision in patients with intermediate and high-risk prostate cancer. A true value of this impact should be defined a large scale prospective clinical trial.