Image-guided radiotherapy reduces the risk of under-dosing high-risk prostate cancer extra-capsular disease and improves biochemical control

Abstract

BackgroundTo determine if reduced dose delivery uncertainty is associated with daily image-guidance (IG) and Prostate Specific Antigen Relapse Free Survival (PRFS) in intensity-modulated radiotherapy (IMRT) of high-risk prostate cancer (PCa).MethodsPlanning data for consecutive PCa patients treated with IMRT (n = 67) and IG-IMRT (n = 35) was retrieved. Using computer simulations of setup errors, we estimated the patient-specific uncertainty in accumulated treatment dose distributions for the prostate and for posterolateral aspects of the gland that are at highest risk for extra-capsular disease. Multivariate Cox regression for PRFS considering Gleason score, T-stage, pre-treatment PSA, number of elevated clinical risk factors (T2c+, GS7+ and PSA10+), nomogram-predicted risk of extra-capsular disease (ECD), and dose metrics was performed.ResultsFor IMRT vs. IG-IMRT, plan dosimetry values were similar, but simulations revealed uncertainty in delivered dose external to the prostate was significantly different, due to positioning uncertainties. A patient-specific interaction term of the risk of ECD and risk of low dose to the ECD (p = 0.005), and the number of elevated clinical risk factors (p = 0.008), correlate with reduced PRFS.ConclusionsImprovements in PSA outcomes for high-risk PCa using IG-IMRT vs. IMRT without IG may be due to improved dosimetry for ECD.Electronic supplementary materialThe online version of this article (10.1186/s13014-018-0978-1) contains supplementary material, which is available to authorized users.

Development of an automated radiotherapy dose accumulation workflow for locally advanced high‐risk prostate cancer – A technical report

“…The majority of the patients will have only one treatment plan generated on the planning CT (pCT) data set prior to treatment. As such, daily variations in organ deformations throughout the course of radiotherapy are not taken into account 2 . The dose received by the prostate and organs at risk (OARs) might be either over or under‐estimated, which has the potential to impact on the local control and radiation‐induced toxicity of the patient 3 …”

The role of image-guided radiotherapy in prostate cancer: A systematic review and meta-analysis

“…After screening titles and abstracts for eligibility, 224 full-text articles were reviewed. After further exclusion, 26 articles were eligible for inclusion, but 6 of them were excluded due to the inappropriate form of outcomes [17] , [37] , [38] , [39] , [40] , [41] and 2 were excluded because of the same cohort of patients [42] , [43] . Ultimately, 18 studies that met the eligibility criteria were finally selected, including 3 RCTs, [19] , [23] , [44] 4 PCSs [45] , [46] , [47] , [48] and 11 RCSs [18] , [21] , [22] , [49] , [50] , [51] , [52] , [53] , [54] , [55] , [56] .…”

4D perfusion CT of prostate cancer for image-guided radiotherapy planning: A proof of concept study

“…In the clinical scenario of patients with histology-proven PCa who are scheduled for focal boost therapy to the macroscopic tumor area, exact tumor structure/lesion delineation using a clinically suitable method is of utmost importance for treatment planning [5,21,22]. The excellent soft tissue contrast of MRI has been proven to accurately delineate PCa [23], while CT has been of limited value thus far in this respect.…”

“…As local recurrences mainly occur at the site of the primary tumor lesion [3], ongoing efforts are being made to establish a boost focused on the tumor tissue, with a current standard dose for the remaining prostate [4]. Based on computerized treatment plan optimization algorithms and respective IMRT-based dose delivery techniques, even multiple clinical target volumes (CTV) with different dose prescriptions can be treated within one treatment session, and, at the same time, reducing the dose to organs at risk (OAR) [5–8].…”