Abstract
We hypothesized that dominant intraprostatic lesions (DILs) could be depictured by multimodal imaging techniques (MRI and/or PSMA PET/CT) in patients with primary prostate cancer (PCa) and investigated possible effects of radiotherapy (RT) dose distribution within the DILs on the patients’ outcome. One hundred thirty-eight patients with localized prostate cancer (PCa) and visible DIL underwent primary external beam RT between 2008 and 2016 with an aimed prescription dose of 76 Gy to the whole prostate. Seventy-five patients (54%) additionally received androgen deprivation therapy. Three volumes were retrospectively generated: DIL using pretreatment MRI and/or PSMA PET/CT, prostatic gland (PG) and the subtraction between PG and DIL (SPG). The minimum dose (Dmin), maximum dose (Dmax) and mean dose (Dmean) in the three respective volumes were calculated. Biochemical recurrence free survival (BRFS) was considered in uni- and multivariate Cox regression analyses. An explorative analysis was performed to determine cut-off values for the three dose parameters in the three respective volumes. With a median follow-up of 45 months (14–116 months) 15.9% of patients experienced BR. Dmin (cut-off: 70.6 Gy, HR = 0.39, p = 0.036) applied to the DIL had an impact on BRFS in multivariate analysis, in contrast to the Dmin delivered to PG and SPG which had no significant impact (p > 0.05). Dmin was significantly (p 0.05). The dose distribution within DILs defined by PSMA PET/CT and/or MRI is an independent risk factor for BR after primary RT in patients with PCa. These findings support the implementation of imaging based DIL interpretation for RT treatment planning, although further validation in larger patient cohorts with longer follow-up is needed.
Highlights
We hypothesized that dominant intraprostatic lesions (DILs) could be depictured by multimodal imaging techniques (MRI and/or prostate specific membrane antigen (PSMA) PET/computed tomography (CT)) in patients with primary prostate cancer (PCa) and investigated possible effects of radiotherapy (RT) dose distribution within the DILs on the patients’ outcome
The dose distribution within DILs defined by PSMA Positron emission tomography/ computed tomography (PET/CT) and/or magnetic resonance imaging (MRI) is an independent risk factor for Biochemical recurrence (BR) after primary RT in patients with PCa
In this retrospective analysis we hypothesized that PSMA PET/CT and multiparametric MRI (mpMRI) are appropriate to localize the DIL (DIL-imaging) and that the dose parameters for Patient and treatment related parameters iPSA in ng/ml (< 10, 10–20, > 20)
Summary
We hypothesized that dominant intraprostatic lesions (DILs) could be depictured by multimodal imaging techniques (MRI and/or PSMA PET/CT) in patients with primary prostate cancer (PCa) and investigated possible effects of radiotherapy (RT) dose distribution within the DILs on the patients’ outcome. Conventional external beam radiation therapy (EBRT) for patients with primary PCa aims at delivering a homogeneous dose to the entire prostatic gland. Three studies examined whether the local recurrences of PCa after primary radiation therapy (RT) occur at the site of primary lesion using pre and post treatment magnetic resonance imaging (MRI) in a limited number of patients, respectively. Sensitivities of 52–85% for MRI [6] and 64–75% for PSMA PET/CT [7,8,9] were reported, suggesting, that not the entire PCa amount is identified by these techniques mainly because of nondetectable microscopic lesions
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