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Moran S, Cheng HH, Weg E, Kim EH, Chen DL, Iravani A, Ippolito JE. Prostate-specific membrane antigen-positron emission tomography (PSMA-PET) of prostate cancer: current and emerging applications. Abdom Radiol (NY) 2024; 49:1288-1305. [PMID: 38386156 DOI: 10.1007/s00261-024-04188-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Revised: 01/03/2024] [Accepted: 01/07/2024] [Indexed: 02/23/2024]
Abstract
Prostate-specific membrane antigen-positron emission tomography (PSMA-PET) is transforming the management of patients with prostate cancer. In appropriately selected patients, PSMA-PET offers superior sensitivity and specificity compared to conventional imaging (e.g., computed tomography and bone scintigraphy) as well as choline and fluciclovine PET, with the added benefit of consolidating bone and soft tissue evaluation into a single study. Despite being a newly available imaging tool, PSMA-PET has established indications, interpretation guidelines, and reporting criteria, which will be reviewed. The prostate cancer care team, from imaging specialists to those delivering treatment, should have knowledge of physiologic PSMA radiotracer uptake, patterns of disease spread, and the strengths and limitations of PSMA-PET. In this review, current and emerging applications of PSMA-PET, including appropriateness use criteria as well as image interpretation and pitfalls, will be provided with an emphasis on clinical implications.
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Affiliation(s)
- Shamus Moran
- Department of Radiology, University of Washington School of Medicine, Seattle, WA, USA
| | - Heather H Cheng
- Division of Oncology, Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Emily Weg
- Department of Radiation Oncology, University of Washington School of Medicine, Seattle, WA, USA
| | - Eric H Kim
- Division of Urologic Surgery, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Delphine L Chen
- Division of Nuclear Medicine, Department of Radiology, University of Washington School of Medicine, Seattle, WA, USA
- Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Amir Iravani
- Division of Nuclear Medicine, Department of Radiology, University of Washington School of Medicine, Seattle, WA, USA
- Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Joseph E Ippolito
- Mallinckrodt Institute of Radiology, Washington University School of Medicine in St. Louis, 4559 Scott Ave., Mail Stop Code: 8131, St. Louis, MO, 63110, USA.
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine in St. Louis, St. Louis, MO, USA.
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Dmochowska N, Milanova V, Mukkamala R, Chow KK, Pham NTH, Srinivasarao M, Ebert LM, Stait-Gardner T, Le H, Shetty A, Nelson M, Low PS, Thierry B. Nanoparticles Targeted to Fibroblast Activation Protein Outperform PSMA for MRI Delineation of Primary Prostate Tumors. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2204956. [PMID: 36840671 DOI: 10.1002/smll.202204956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 01/23/2023] [Indexed: 05/25/2023]
Abstract
Accurate delineation of gross tumor volumes remains a barrier to radiotherapy dose escalation and boost dosing in the treatment of solid tumors, such as prostate cancer. Magnetic resonance imaging (MRI) of tumor targets has the power to enable focal dose boosting, particularly when combined with technological advances such as MRI-linear accelerator. Fibroblast activation protein (FAP) is overexpressed in stromal components of >90% of epithelial carcinomas. Herein, the authors compare targeted MRI of prostate specific membrane antigen (PSMA) with FAP in the delineation of orthotopic prostate tumors. Control, FAP, and PSMA-targeting iron oxide nanoparticles were prepared with modification of a lymphotropic MRI agent (FerroTrace, Ferronova). Mice with orthotopic LNCaP tumors underwent MRI 24 h after intravenous injection of nanoparticles. FAP and PSMA nanoparticles produced contrast enhancement on MRI when compared to control nanoparticles. FAP-targeted MRI increased the proportion of tumor contrast-enhancing black pixels by 13%, compared to PSMA. Analysis of changes in R2 values between healthy prostates and LNCaP tumors indicated an increase in contrast-enhancing pixels in the tumor border of 15% when targeting FAP, compared to PSMA. This study demonstrates the preclinical feasibility of PSMA and FAP-targeted MRI which can enable targeted image-guided focal therapy of localized prostate cancer.
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Affiliation(s)
- Nicole Dmochowska
- Future Industries Institute, University of South Australia, Adelaide, South Australia, 5095, Australia
| | - Valentina Milanova
- Future Industries Institute, University of South Australia, Adelaide, South Australia, 5095, Australia
| | - Ramesh Mukkamala
- Department of Chemistry and Institute for Drug Discovery, Purdue University, West Lafayette, IN, 47907, USA
| | - Kwok Keung Chow
- Future Industries Institute, University of South Australia, Adelaide, South Australia, 5095, Australia
| | - Nguyen T H Pham
- Key Centre for Polymers and Colloids, School of Chemistry, The University of Sydney, Sydney, New South Wales, 2006, Australia
| | - Madduri Srinivasarao
- Department of Chemistry and Institute for Drug Discovery, Purdue University, West Lafayette, IN, 47907, USA
| | - Lisa M Ebert
- Centre for Cancer Biology, University of South Australia; SA Pathology; Cancer Clinical Trials Unit, Royal Adelaide Hospital; Adelaide Medical School, University of Adelaide, Adelaide, South Australia, 5000, Australia
| | - Timothy Stait-Gardner
- Nanoscale Organisation and Dynamics Group, Western Sydney University, Sydney, New South Wales, 2560, Australia
| | - Hien Le
- Department of Radiation Oncology, Royal Adelaide Hospital, Adelaide, South Australia, 5000, Australia
| | - Anil Shetty
- Ferronova Pty Ltd, Mawson Lakes, South Australia, 5095, Australia
| | - Melanie Nelson
- Ferronova Pty Ltd, Mawson Lakes, South Australia, 5095, Australia
| | - Philip S Low
- Department of Chemistry and Institute for Drug Discovery, Purdue University, West Lafayette, IN, 47907, USA
| | - Benjamin Thierry
- Future Industries Institute, University of South Australia, Adelaide, South Australia, 5095, Australia
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Luminais CK, Nourzadeh H, Aliotta E, Ward K, Cousins D, Showalter TN, Libby B. Dose differentiated high-dose-rate prostate brachytherapy: a feasibility assessment of MRI-guided dose escalation to dominant intra-prostatic lesions. J Contemp Brachytherapy 2022; 14:423-428. [PMID: 36478705 PMCID: PMC9720688 DOI: 10.5114/jcb.2022.120035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 08/29/2022] [Indexed: 09/27/2023] Open
Abstract
PURPOSE Prostate brachytherapy is routinely performed with trans-rectal ultrasound (TRUS)- or computed tomography (CT)-based planning that cannot delineate dominant intra-prostatic lesions (DILs). In contrast, magnetic resonance imaging (MRI)-based planning allows for more accurate DIL delineation and dose escalation. This study assessed the maximum achievable dose escalation to DILs. MATERIAL AND METHODS We retrospectively identified 24 patients treated with high-dose-rate (HDR) prostate brachytherapy boost (15 Gy in 1 fraction). All patients had a pre-treatment prostate MRI with 1-3 DILs. MRIs were used to delineate DILs and were co-registered to TRUS intra-procedure. Treatment plans were experimentally re-optimized to escalate DIL dose. Dosimetric indices from the original and re-optimized plans were compared using two-tailed paired t-test. Re-optimized plans were deemed acceptable if they achieved all of the following criteria: prostate D90 > 100%, prostate V100 > 90%, urethra D10 < 118%, rectum V80 < 0.5 cc, bladder D1cc < 75%, or if they did not exceed organs at risk (OARs) doses of the original plan. RESULTS The mean DIL D90 was significantly increased from 134% of the prescription dose on the original plans to 154% on the re-optimized plans. The mean urethra D10 and mean bladder D1cc were significantly reduced from 123% to 117% and from 72% to 65%, respectively. Prostate D90 was reduced from 106% to 102%, and prostate V100 was reduced from 93% to 91%. CONCLUSIONS We re-optimized HDR brachytherapy plans to escalate DILs dose to a mean D90 of > 150% while maintaining favorable prostate coverage and OARs doses. We propose DIL D90 dose of > 150% (22.5 Gy) as an achievable goal.
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Affiliation(s)
| | - Hamidreza Nourzadeh
- Department of Radiation Oncology, University of Virginia, Charlottesville, Virginia, USA
| | - Eric Aliotta
- Department of Radiation Oncology, University of Virginia, Charlottesville, Virginia, USA
| | - Kristin Ward
- Department of Radiation Oncology, University of Virginia, Charlottesville, Virginia, USA
| | - David Cousins
- Department of Radiation Oncology, University of Virginia, Charlottesville, Virginia, USA
| | - Timothy N. Showalter
- Department of Radiation Oncology, University of Virginia, Charlottesville, Virginia, USA
| | - Bruce Libby
- Moffitt Cancer Center, University of South Florida, USA
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Liu W, Loblaw A, Laidley D, Fakir H, Mendez L, Davidson M, Kassam Z, Lee TY, Ward A, Thiessen J, Bayani J, Conyngham J, Bailey L, Andrews JD, Bauman G. Imaging Biomarkers in Prostate Stereotactic Body Radiotherapy: A Review and Clinical Trial Protocol. Front Oncol 2022; 12:863848. [PMID: 35494042 PMCID: PMC9043802 DOI: 10.3389/fonc.2022.863848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 03/07/2022] [Indexed: 11/13/2022] Open
Abstract
Advances in imaging have changed prostate radiotherapy through improved biochemical control from focal boost and improved detection of recurrence. These advances are reviewed in the context of prostate stereotactic body radiation therapy (SBRT) and the ARGOS/CLIMBER trial protocol. ARGOS/CLIMBER will evaluate 1) the safety and feasibility of SBRT with focal boost guided by multiparametric MRI (mpMRI) and 18F-PSMA-1007 PET and 2) imaging and laboratory biomarkers for response to SBRT. To date, response to prostate SBRT is most commonly evaluated using the Phoenix Criteria for biochemical failure. The drawbacks of this approach include lack of lesion identification, a high false-positive rate, and delay in identifying treatment failure. Patients in ARGOS/CLIMBER will receive dynamic 18F-PSMA-1007 PET and mpMRI prior to SBRT for treatment planning and at 6 and 24 months after SBRT to assess response. Imaging findings will be correlated with prostate-specific antigen (PSA) and biopsy results, with the goal of early, non-invasive, and accurate identification of treatment failure.
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Affiliation(s)
- Wei Liu
- Department of Oncology, Division of Radiation Oncology, London Health Sciences Centre and Western University, London, ON, Canada
| | - Andrew Loblaw
- Department of Radiation Oncology, Odette Cancer Center, Sunnybrook Health Sciences Centre and Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada
| | - David Laidley
- Division of Nuclear Medicine, St. Joseph's Health Centre and Western University, London, ON, Canada
| | - Hatim Fakir
- Department of Oncology and Department of Medical Biophysics, London Health Sciences Centre and Western University, London, ON, Canada
| | - Lucas Mendez
- Department of Oncology, Division of Radiation Oncology, London Health Sciences Centre and Western University, London, ON, Canada
| | - Melanie Davidson
- Department of Radiation Oncology, Odette Cancer Center, Sunnybrook Health Sciences Centre and Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada
| | - Zahra Kassam
- Department of Medical Imaging, St. Joseph's Health Care and Western University, London, ON, Canada
| | - Ting-Yim Lee
- Department of Medical Biophysics, Western University and Lawson Health Research Institute, London, ON, Canada
| | - Aaron Ward
- Department of Medical Biophysics, Western University and Lawson Health Research Institute, London, ON, Canada
| | - Jonathan Thiessen
- Department of Medical Biophysics, Western University and Lawson Health Research Institute, London, ON, Canada
| | - Jane Bayani
- Ontario Institute for Cancer Research and Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | | | - Laura Bailey
- Clinical Research Unit, London Regional Cancer Program, London, ON, Canada
| | - Joseph D Andrews
- Clinical Research Unit, London Regional Cancer Program, London, ON, Canada
| | - Glenn Bauman
- Department of Oncology, Division of Radiation Oncology, London Health Sciences Centre and Western University, London, ON, Canada
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Naccarato S, Rigo M, Pellegrini R, Voet P, Akhiat H, Gurrera D, De Simone A, Sicignano G, Mazzola R, Figlia V, Ricchetti F, Nicosia L, Giaj-Levra N, Cuccia F, Stavreva N, Pressyanov DS, Stavrev P, Alongi F, Ruggieri R. Automated Planning for Prostate Stereotactic Body Radiation Therapy on the 1.5 T MR-Linac. Adv Radiat Oncol 2022; 7:100865. [PMID: 35198836 PMCID: PMC8850203 DOI: 10.1016/j.adro.2021.100865] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 10/19/2021] [Indexed: 11/25/2022] Open
Abstract
Purpose Adaptive stereotactic body radiation therapy (SBRT) for prostate cancer (PC) by the 1.5 T MR-linac currently requires online planning by an expert user. A fully automated and user-independent solution to adaptive planning (mCycle) of PC-SBRT was compared with user's plans for the 1.5 T MR-linac. Methods and Materials Fifty adapted plans on daily magnetic resonance imaging scans for 10 patients with PC treated by 35 Gy (prescription dose [Dp]) in 5 fractions were reoptimized offline from scratch, both by an expert planner (manual) and by mCycle. Manual plans consisted of multicriterial optimization (MCO) of the fluence map plus manual tweaking in segmentation, whereas in mCycle plans, the objectives were sequentially optimized by MCO according to an a-priori assigned priority list. The main criteria for planning approval were a dose ≥95% of the Dp to at least 95% of the planning target volume (PTV), V33.2 (PTV) ≥ 95%, a dose less than the Dp to the hottest cubic centimeter (V35 ≤ 1 cm3) of rectum, bladder, penile bulb, and urethral planning risk volume (ie, urethra plus 3 mm isotropically), and V32 ≤ 5%, V28 ≤ 10%, and V18 ≤ 35% to the rectum. Such dose-volume metrics, plus some efficiency and deliverability metrics, were used for the comparison of mCycle versus manual plans. Results mCycle plans improved target dose coverage, with V33.2 (PTV) passing on average (±1 SD) from 95.7% (±1.0%) for manual plans to 97.5% (±1.3%) for mCycle plans (P < .001), and rectal dose sparing, with significantly reduced V32, V28, and V18 (P ≤ .004). Although at an equivalent number of segments, mCycle plans consumed moderately more monitor units (+17%) and delivery time (+9%) (P < .001), whereas they were generally faster (–19%) in terms of optimization times (P < .019). No significant differences were found for the passing rates of locally normalized γ (3 mm, 3%) (P = .059) and γ (2 mm, 2%) (P = .432) deliverability metrics. Conclusions In the offline setting, mCycle proved to be a trustable solution for automated planning of PC-SBRT on the 1.5 T MR-linac. mCycle integration in the online workflow will free the user from the challenging online-optimization task.
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Feasibility of biology-guided radiotherapy using PSMA-PET to boost to dominant intraprostatic tumour. Clin Transl Radiat Oncol 2022; 35:84-89. [PMID: 35662883 PMCID: PMC9156937 DOI: 10.1016/j.ctro.2022.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 05/11/2022] [Accepted: 05/13/2022] [Indexed: 11/23/2022] Open
Abstract
Biology-guided radiation therapy (BGRT) uses PET imaging for online image guidance. PSMA PET uptake is abundant in the dominant intraprostatic lesion (DIL). BgRT boost to PSMA-avid subvolume in the prostate region may be feasible. Suitable targets for BgRT were identified in the ProPSMA clinical trial.
Background Methods Results Conclusions
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7
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Wu YY, Fan KH. Proton therapy for prostate cancer: current state and future perspectives. Br J Radiol 2022; 95:20210670. [PMID: 34558308 PMCID: PMC8978248 DOI: 10.1259/bjr.20210670] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
OBJECTIVE Localized prostate cancer can be treated with several radiotherapeutic approaches. Proton therapy (PT) can precisely target tumors, thus sparing normal tissues and reducing side-effects without sacrificing cancer control. However, PT is a costly treatment compared with conventional photon radiotherapy, which may undermine its overall efficacy. In this review, we summarize current data on the dosimetric rationale, clinical benefits, and cost of PT for prostate cancer. METHODS An extensive literature review of PT for prostate cancer was performed with emphasis on studies investigating dosimetric advantage, clinical outcomes, cost-effective strategies, and novel technology trends. RESULTS PT is safe, and its efficacy is comparable to that of standard photon-based therapy or brachytherapy. Data on gastrointestinal, genitourinary, and sexual function toxicity profiles are conflicting; however, PT is associated with a low risk of second cancer and has no effects on testosterone levels. Regarding cost-effectiveness, PT is suboptimal, although evolving trends in radiation delivery and construction of PT centers may help reduce the cost. CONCLUSION PT has several advantages over conventional photon radiotherapy, and novel approaches may increase its efficacy and safety. Large prospective randomized trials comparing photon therapy with proton-based treatments are ongoing and may provide data on the differences in efficacy, toxicity profile, and quality of life between proton- and photon-based treatments for prostate cancer in the modern era. ADVANCES IN KNOWLEDGE PT provides excellent physical advantages and has a superior dose profile compared with X-ray radiotherapy. Further evidence from clinical trials and research studies will clarify the role of PT in the treatment of prostate cancer, and facilitate the implementation of PT in a more accessible, affordable, efficient, and safe way.
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Affiliation(s)
- Yao-Yu Wu
- Department of Radiation Oncology, Linkou Chang Gung Memorial Hospital and Chang Gung University, Taoyuan City, Taiwan
| | - Kang-Hsing Fan
- Department of Radiation Oncology, New Taipei Municipal TuCheng Hospital, Chang Gung Memorial Hospital and Chang Gung University, Taoyuan, Taiwan
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Greco C, Pares O, Pimentel N, Louro V, Nunes B, Kociolek J, Marques J, Fuks Z. Early PSA density kinetics predicts biochemical and local failure following extreme hypofractionated radiotherapy in intermediate-risk prostate cancer. Radiother Oncol 2022; 169:35-42. [DOI: 10.1016/j.radonc.2022.02.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 02/05/2022] [Accepted: 02/14/2022] [Indexed: 10/19/2022]
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Moteabbed M, Harisinghani M, Paganetti H, Trofimov A, Lu HM, Efstathiou JA. Proton vs. photon radiotherapy for MR-guided dose escalation of intraprostatic lesions. Acta Oncol 2021; 60:1283-1290. [PMID: 34282708 DOI: 10.1080/0284186x.2021.1947523] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Dose escalation has been associated with improved biochemical control for prostate cancer. Focusing the high dose on the MRI-defined intraprostatic lesions (IL) could spare the surrounding organs at risk and hence allow further escalation. We compare treatment efficacy between state-of-the-art focally-boosted proton and photon-based radiotherapy, and investigate possible predictive guidelines regarding individualized treatment prescriptions. MATERIAL AND METHODS Ten prostate cancer patients with well-defined ILs were selected. Multiparametric MRI was used to delineate ILs, which were transferred to the planning CT via image registration. Pencil beam scanning proton therapy and volumetric modulated arc therapy treatment plans, were created for each patient. Each modality featured 6 plans: (1) moderately hypofractionated dose: 70 Gy to the prostate in 28 fractions, (2)-(6) plan 1 plus additional simultaneous-integrated-boost to ILs to 75.6, 81.2, 86.6, 98 and 112 Gy in 28 fractions. Equivalent dose to 2 Gy-per-fraction (EqD2) was used to calculate tumor control (TCP) and normal tissue complication probabilities (NTCP) for ILs and organs-at-risk. RESULTS For both modalities, the maximum necessary dose to achieve TCP > 99% was 98 Gy for very high-risk ILs. For lower risk ILs lower doses were sufficient. NTCP was <25% and 35% for protons and photons at the maximum dose escalation, respectively. For the cases and beam characteristics considered, proton therapy was dosimetrically superior when IL was >4 cc or located <2.5 mm from the rectum. CONCLUSION This work demonstrated the potential role for proton therapy in the setting of prostate focal dose escalation. We propose that anatomical characteristic could be used as criteria to identify patients who would benefit from proton treatment.
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Affiliation(s)
- Maryam Moteabbed
- Division of Radiation Biophysics, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Mukesh Harisinghani
- Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Harald Paganetti
- Division of Radiation Biophysics, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Alexei Trofimov
- Division of Radiation Biophysics, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | | | - Jason A. Efstathiou
- Division of Radiation Biophysics, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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Sepulcri M, Fusella M, Cuppari L, Zorz A, Paiusco M, Evangelista L. Value of 18F-fluorocholine PET/CT in predicting response to radical radiotherapy in patients with localized prostate cancer. Clin Transl Radiat Oncol 2021; 30:71-77. [PMID: 34409175 PMCID: PMC8361027 DOI: 10.1016/j.ctro.2021.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 07/07/2021] [Accepted: 07/18/2021] [Indexed: 11/16/2022] Open
Abstract
PURPOSE This study aims to establish whether metabolic parameters obtainable from FCH PET/CT can predict long-term response to radical radiotherapy (rRT) in patients with localized prostate cancer (PCa). METHODS Drawing on a single-center database, we retrospectively reviewed the pre-treatment FCH PET/CT scans of 50 patients who underwent rRT between 2012 and 2017. Patients were enrolled if they had a follow-up of at least 3 years after rRT. Various metabolic parameters were considered for each PET/CT, including FCH multifocality. rRT was administered to all patients for a total equivalent dose of 76-80 Gy, using a standard or hypofractionated schedule. Patients were classified as disease-free (DF) if their PSA levels after rRT rose by <2 ng/mL vis-à-vis their PSA nadir, or as not disease free (NDF) if their PSA levels rose by more than 2 ng/ml. RESULTS A multifocal FCH uptake in the prostate gland was identified in 27 patients (54%). At 3-year follow-up, 37 patients (74%) were judged DF, and 13 (26%) were NDF. The SUVmax and SUVmean, and the sum of the two values in all FCH foci in the prostate gland were significantly higher for NDF patients than for DF patients (all p < 0.005). The sum of the TLCKA levels in all FCH foci was likewise significantly higher in patients who were NDF than in those found DF (median 54.5 vs. 29.4; p < 0.05). At univariate analysis, the most of PET-metrics and Gleason Score were predictors of biochemical relapse after 3-year follow-up (all p < 0.05). CONCLUSION Higher SUVs seems predict a worse outcome for patients with multifocal intraprostatic lesions who are candidates for rRT.
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Affiliation(s)
- Matteo Sepulcri
- Department of Radiation Oncology, Veneto Institute of Oncology IOV-IRCCS, Padua, Italy
| | - Marco Fusella
- Department of Medical Physics, Veneto Institute of Oncology IOV-IRCCS, Padua, Italy
| | - Lea Cuppari
- Nuclear Medicine Unit, Veneto Institute of Oncology IOV-IRCCS, Padua, Italy
| | - Alessandra Zorz
- Department of Medical Physics, Veneto Institute of Oncology IOV-IRCCS, Padua, Italy
| | - Marta Paiusco
- Department of Medical Physics, Veneto Institute of Oncology IOV-IRCCS, Padua, Italy
| | - Laura Evangelista
- Nuclear Medicine Unit, Department of Medicine DIMED, University of Padua, Padua, Italy
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11
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Spohn SKB, Sachpazidis I, Wiehle R, Thomann B, Sigle A, Bronsert P, Ruf J, Benndorf M, Nicolay NH, Sprave T, Grosu AL, Baltas D, Zamboglou C. Influence of Urethra Sparing on Tumor Control Probability and Normal Tissue Complication Probability in Focal Dose Escalated Hypofractionated Radiotherapy: A Planning Study Based on Histopathology Reference. Front Oncol 2021; 11:652678. [PMID: 34055621 PMCID: PMC8160377 DOI: 10.3389/fonc.2021.652678] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 04/08/2021] [Indexed: 11/13/2022] Open
Abstract
Purpose Multiparametric magnetic resonance tomography (mpMRI) and prostate specific membrane antigen positron emission tomography (PSMA-PET/CT) are used to guide focal radiotherapy (RT) dose escalation concepts. Besides improvements of treatment effectiveness, maintenance of a good quality of life is essential. Therefore, this planning study investigates whether urethral sparing in moderately hypofractionated RT with focal RT dose escalation influences tumour control probability (TCP) and normal tissue complication probability (NTCP). Patients and Methods 10 patients with primary prostate cancer (PCa), who underwent 68Ga PSMA-PET/CT and mpMRI followed by radical prostatectomy were enrolled. Intraprostatic tumour volumes (gross tumor volume, GTV) based on both imaging techniques (GTV-MRI and -PET) were contoured manually using validated contouring techniques and GTV-Union was created by summing both. For each patient three IMRT plans were generated with 60 Gy to the whole prostate and a simultaneous integrated boost up to 70 Gy to GTV-Union in 20 fractions by (Plan 1) not respecting and (Plan 2) respecting dose constraints for urethra as well as (Plan 3) respecting dose constraints for planning organ at risk volume for urethra (PRV = urethra + 2mm expansion). NTCP for urethra was calculated applying a Lyman-Kutcher-Burman model. TCP-Histo was calculated based on PCa distribution in co-registered histology (GTV-Histo). Complication free tumour control probability (P+) was calculated. Furthermore, the intrafractional movement was considered. Results Median overlap of GTV-Union and PRV-Urethra was 1.6% (IQR 0-7%). Median minimum distance of GTV-Histo to urethra was 3.6 mm (IQR 2 - 7 mm) and of GTV-Union to urethra was 1.8 mm (IQR 0.0 - 5.0 mm). The respective prescription doses and dose constraints were reached in all plans. Urethra-sparing in Plans 2 and 3 reached significantly lower NTCP-Urethra (p = 0.002) without significantly affecting TCP-GTV-Histo (p = p > 0.28), NTCP-Bladder (p > 0.85) or NTCP-Rectum (p = 0.85), resulting in better P+ (p = 0.006). Simulation of intrafractional movement yielded even higher P+ values for Plans 2 and 3 compared to Plan 1. Conclusion Urethral sparing may increase the therapeutic ratio and should be implemented in focal RT dose escalation concepts.
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Affiliation(s)
- Simon K B Spohn
- Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK). Partner Site Freiburg, Freiburg, Germany.,Berta-Ottenstein-Programme, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ilias Sachpazidis
- Division of Medical Physics, Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Rolf Wiehle
- Division of Medical Physics, Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Benedikt Thomann
- Division of Medical Physics, Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - August Sigle
- Department of Urology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Peter Bronsert
- Institute for Surgical Pathology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Juri Ruf
- Department of Nuclear Medicine, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Matthias Benndorf
- Department of Radiology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Nils H Nicolay
- Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK). Partner Site Freiburg, Freiburg, Germany
| | - Tanja Sprave
- Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK). Partner Site Freiburg, Freiburg, Germany
| | - Anca L Grosu
- Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK). Partner Site Freiburg, Freiburg, Germany
| | - Dimos Baltas
- German Cancer Consortium (DKTK). Partner Site Freiburg, Freiburg, Germany.,Division of Medical Physics, Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Constantinos Zamboglou
- Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK). Partner Site Freiburg, Freiburg, Germany.,Berta-Ottenstein-Programme, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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12
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Spohn SKB, Kramer M, Kiefer S, Bronsert P, Sigle A, Schultze-Seemann W, Jilg CA, Sprave T, Ceci L, Fassbender TF, Nicolay NH, Ruf J, Grosu AL, Zamboglou C. Comparison of Manual and Semi-Automatic [ 18F]PSMA-1007 PET Based Contouring Techniques for Intraprostatic Tumor Delineation in Patients With Primary Prostate Cancer and Validation With Histopathology as Standard of Reference. Front Oncol 2020; 10:600690. [PMID: 33365271 PMCID: PMC7750498 DOI: 10.3389/fonc.2020.600690] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 11/04/2020] [Indexed: 01/05/2023] Open
Abstract
PURPOSE Accurate contouring of intraprostatic gross tumor volume (GTV) is pivotal for successful delivery of focal therapies and for biopsy guidance in patients with primary prostate cancer (PCa). Contouring of GTVs, using 18-Fluor labeled tracer prostate specific membrane antigen positron emission tomography ([18F]PSMA-1007/PET) has not been examined yet. PATIENTS AND METHODS Ten Patients with primary PCa who underwent [18F]PSMA-1007 PET followed by radical prostatectomy were prospectively enrolled. Coregistered histopathological gross tumor volume (GTV-Histo) was used as standard of reference. PSMA-PET images were contoured on two ways: (1) manual contouring with PET scaling SUVmin-max: 0-10 was performed by three teams with different levels of experience. Team 1 repeated contouring at a different time point, resulting in n = 4 manual contours. (2) Semi-automatic contouring approaches using SUVmax thresholds of 20-50% were performed. Interobserver agreement was assessed for manual contouring by calculating the Dice Similarity Coefficient (DSC) and for all approaches sensitivity, specificity were calculated by dividing the prostate in each CT slice into four equal quadrants under consideration of histopathology as standard of reference. RESULTS Manual contouring yielded an excellent interobserver agreement with a median DSC of 0.90 (range 0.87-0.94). Volumes derived from scaling SUVmin-max 0-10 showed no statistically significant difference from GTV-Histo and high sensitivities (median 87%, range 84-90%) and specificities (median 96%, range 96-100%). GTVs using semi-automatic segmentation applying a threshold of 20-40% of SUVmax showed no significant difference in absolute volumes to GTV-Histo, GTV-SUV50% was significantly smaller. Best performing semi-automatic contour (GTV-SUV20%) achieved high sensitivity (median 93%) and specificity (median 96%). There was no statistically significant difference to SUVmin-max 0-10. CONCLUSION Manual contouring with PET scaling SUVmin-max 0-10 and semi-automatic contouring applying a threshold of 20% of SUVmax achieved high sensitivities and very high specificities and are recommended for [18F]PSMA-1007 PET based focal therapy approaches. Providing high specificities, semi-automatic approaches applying thresholds of 30-40% of SUVmax are recommend for biopsy guidance.
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Affiliation(s)
- Simon K. B. Spohn
- Department of Radiation Oncology, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
| | - Maria Kramer
- Department of Radiation Oncology, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Selina Kiefer
- Institute for Surgical Pathology, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Peter Bronsert
- Institute for Surgical Pathology, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - August Sigle
- Department of Urology, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Wolfgang Schultze-Seemann
- Department of Urology, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Cordula A. Jilg
- Department of Urology, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Tanja Sprave
- Department of Radiation Oncology, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
| | - Lara Ceci
- Department of Radiation Oncology, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Thomas F. Fassbender
- Department of Nuclear Medicine, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Nils H. Nicolay
- Department of Radiation Oncology, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
| | - Juri Ruf
- Department of Nuclear Medicine, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Anca L. Grosu
- Department of Radiation Oncology, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
| | - Constantinos Zamboglou
- Department of Radiation Oncology, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
- Berta-Ottenstein-Programme, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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13
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Kostyszyn D, Fechter T, Bartl N, Grosu AL, Gratzke C, Sigle A, Mix M, Ruf J, Fassbender TF, Kiefer S, Bettermann AS, Nicolay NH, Spohn S, Kramer MU, Bronsert P, Guo H, Qiu X, Wang F, Henkenberens C, Werner RA, Baltas D, Meyer PT, Derlin T, Chen M, Zamboglou C. Intraprostatic Tumor Segmentation on PSMA PET Images in Patients with Primary Prostate Cancer with a Convolutional Neural Network. J Nucl Med 2020; 62:823-828. [PMID: 33127624 DOI: 10.2967/jnumed.120.254623] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 10/07/2020] [Indexed: 12/22/2022] Open
Abstract
Accurate delineation of the intraprostatic gross tumor volume (GTV) is a prerequisite for treatment approaches in patients with primary prostate cancer (PCa). Prostate-specific membrane antigen PET (PSMA PET) may outperform MRI in GTV detection. However, visual GTV delineation underlies interobserver heterogeneity and is time consuming. The aim of this study was to develop a convolutional neural network (CNN) for automated segmentation of intraprostatic tumor (GTV-CNN) in PSMA PET. Methods: The CNN (3D U-Net) was trained on the 68Ga-PSMA PET images of 152 patients from 2 different institutions, and the training labels were generated manually using a validated technique. The CNN was tested on 2 independent internal (cohort 1: 68Ga-PSMA PET, n = 18 and cohort 2: 18F-PSMA PET, n = 19) and 1 external (cohort 3: 68Ga-PSMA PET, n = 20) test datasets. Accordance between manual contours and GTV-CNN was assessed with the Dice-Sørensen coefficient (DSC). Sensitivity and specificity were calculated for the 2 internal test datasets (cohort 1: n = 18, cohort 2: n = 11) using whole-mount histology. Results: The median DSCs for cohorts 1-3 were 0.84 (range: 0.32-0.95), 0.81 (range: 0.28-0.93), and 0.83 (range: 0.32-0.93), respectively. Sensitivities and specificities for the GTV-CNN were comparable with manual expert contours: 0.98 and 0.76 (cohort 1) and 1 and 0.57 (cohort 2), respectively. Computation time was around 6 s for a standard dataset. Conclusion: The application of a CNN for automated contouring of intraprostatic GTV in 68Ga-PSMA and 18F-PSMA PET images resulted in a high concordance with expert contours and in high sensitivities and specificities in comparison with histology as a reference. This robust, accurate and fast technique may be implemented for treatment concepts in primary prostate cancer. The trained model and the study's source code are available in an open source repository.
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Affiliation(s)
- Dejan Kostyszyn
- Division of Medical Physics, Department of Radiation Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Faculty of Engineering, University of Freiburg, Freiburg, Germany
| | - Tobias Fechter
- Division of Medical Physics, Department of Radiation Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, Germany.,Department of Radiation Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Nico Bartl
- German Cancer Consortium (DKTK), Partner Site Freiburg, Germany.,Department of Radiation Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Anca L Grosu
- German Cancer Consortium (DKTK), Partner Site Freiburg, Germany.,Department of Radiation Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Christian Gratzke
- Department of Urology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - August Sigle
- Department of Urology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Michael Mix
- Department of Nuclear Medicine, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Juri Ruf
- Department of Nuclear Medicine, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Thomas F Fassbender
- Department of Nuclear Medicine, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Selina Kiefer
- Institute for Surgical Pathology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Alisa S Bettermann
- Department of Radiation Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Nils H Nicolay
- German Cancer Consortium (DKTK), Partner Site Freiburg, Germany.,Department of Radiation Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Simon Spohn
- German Cancer Consortium (DKTK), Partner Site Freiburg, Germany.,Department of Radiation Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Maria U Kramer
- Department of Radiation Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Peter Bronsert
- German Cancer Consortium (DKTK), Partner Site Freiburg, Germany.,Institute for Surgical Pathology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Hongqian Guo
- Department of Urology, Medical School of Nanjing University, Affiliated Drum Tower Hospital, Nanjing, China
| | - Xuefeng Qiu
- Department of Urology, Medical School of Nanjing University, Affiliated Drum Tower Hospital, Nanjing, China
| | - Feng Wang
- Department of Nuclear Medicine, Medical School of Nanjing University, Affiliated Drum Tower Hospital, Nanjing, China
| | | | - Rudolf A Werner
- Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany
| | - Dimos Baltas
- Division of Medical Physics, Department of Radiation Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, Germany
| | - Philipp T Meyer
- Department of Nuclear Medicine, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Thorsten Derlin
- Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany
| | - Mengxia Chen
- Department of Urology, Medical School of Nanjing University, Affiliated Drum Tower Hospital, Nanjing, China
| | - Constantinos Zamboglou
- German Cancer Consortium (DKTK), Partner Site Freiburg, Germany .,Department of Radiation Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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14
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Sachpazidis I, Mavroidis P, Zamboglou C, Klein CM, Grosu AL, Baltas D. Prostate cancer tumour control probability modelling for external beam radiotherapy based on multi-parametric MRI-GTV definition. Radiat Oncol 2020; 15:242. [PMID: 33081804 PMCID: PMC7574270 DOI: 10.1186/s13014-020-01683-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 10/06/2020] [Indexed: 12/13/2022] Open
Abstract
Purpose To evaluate the applicability and estimate the radiobiological parameters of linear-quadratic Poisson tumour control probability (TCP) model for primary prostate cancer patients for two relevant target structures (prostate gland and GTV). The TCP describes the dose–response of prostate after definitive radiotherapy (RT). Also, to analyse and identify possible significant correlations between clinical and treatment factors such as planned dose to prostate gland, dose to GTV, volume of prostate and mpMRI-GTV based on multivariate logistic regression model.
Methods The study included 129 intermediate and high-risk prostate cancer patients (cN0 and cM0), who were treated with image-guided intensity modulated radiotherapy (IMRT) ± androgen deprivation therapy with a median follow-up period of 81.4 months (range 42.0–149.0) months. Tumour control was defined as biochemical relapse free survival according to the Phoenix definition (BRFS). MpMRI-GTV was delineated retrospectively based on a pre-treatment multi-parametric MR imaging (mpMRI), which was co-registered to the planning CT. The clinical treatment planning procedure was based on prostate gland, delineated on CT imaging modality. Furthermore, we also fitted the clinical data to TCP model for the two considered targets for the 5-year follow-up after radiation treatment, where our cohort was composed of a total number of 108 patients, of which 19 were biochemical relapse (BR) patients. Results For the median follow-up period of 81.4 months (range 42.0–149.0) months, our results indicated an appropriate α/β = 1.3 Gy for prostate gland and α/β = 2.9 Gy for mpMRI-GTV. Only for prostate gland, EQD2 and gEUD2Gy were significantly lower in the biochemical relapse (BR) group compared to the biochemical control (BC) group. Fitting results to the linear-quadratic Poisson TCP model for prostate gland and α/β = 1.3 Gy were D50 = 66.8 Gy with 95% CI [64.6 Gy, 69.0 Gy], and γ = 3.8 with 95% CI [2.6, 5.2]. For mpMRI-GTV and α/β = 2.9 Gy, D50 was 68.1 Gy with 95% CI [66.1 Gy, 70.0 Gy], and γ = 4.5 with 95% CI [3.0, 6.1]. Finally, for the 5-year follow-up after the radiation treatment, our results for the prostate gland were: D50 = 64.6 Gy [61.6 Gy, 67.4 Gy], γ = 3.1 [2.0, 4.4], α/β = 2.2 Gy (95% CI was undefined). For the mpMRI-GTV, the optimizer was unable to deliver any reasonable results for the expected clinical D50 and α/β. The results for the mpMRI-GTV were D50 = 50.1 Gy [44.6 Gy, 56.0 Gy], γ = 0.8 [0.5, 1.2], α/β = 0.0 Gy (95% CI was undefined). For a follow-up time of 5 years and a fixed α/β = 1.6 Gy, the TCP fitting results for prostate gland were D50 = 63.9 Gy [60.8 Gy, 67.0 Gy], γ = 2.9 [1.9, 4.1], and for mpMRI-GTV D50 = 56.3 Gy [51.6 Gy, 61.1 Gy], γ = 1.3 [0.8, 1.9]. Conclusion The linear-quadratic Poisson TCP model was better fit when the prostate gland was considered as responsible target than with mpMRI-GTV. This is compatible with the results of the comparison of the dose distributions among BR and BC groups and with the results achieved with the multivariate logistic model regarding gEUD2Gy. Probably limitations of mpMRI in defining the GTV explain these results. Another explanation could be the relatively homogeneous dose prescription and the relatively low number of recurrences. The failure to identify any benefit for considering mpMRI-GTV as the target responsible for the clinical response is confirmed when considering a fixed α/β = 1.6 Gy, a fixed follow-up time for biochemical response at 5 years or Gleason score differentiation.
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Affiliation(s)
- Ilias Sachpazidis
- Department of Radiation Oncology, Division of Medical Physics, Medical Centre, Faculty of Medicine, University of Freiburg, Robert-Koch-Str. 3, 79106, Freiburg, Germany. .,German Cancer Consortium (DKTK) Partner Site Freiburg, German Cancer Research Centre (DKFZ), Heidelberg, Germany.
| | - Panayiotis Mavroidis
- Department of Radiation Oncology, University of North Carolina, Chapel Hill, NC, USA
| | - Constantinos Zamboglou
- Department of Radiation Oncology, Medical Centre, University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK) Partner Site Freiburg, German Cancer Research Centre (DKFZ), Heidelberg, Germany
| | - Christina Marie Klein
- Department of Radiation Oncology, Medical Centre, University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK) Partner Site Freiburg, German Cancer Research Centre (DKFZ), Heidelberg, Germany
| | - Anca-Ligia Grosu
- Department of Radiation Oncology, Medical Centre, University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK) Partner Site Freiburg, German Cancer Research Centre (DKFZ), Heidelberg, Germany
| | - Dimos Baltas
- Department of Radiation Oncology, Division of Medical Physics, Medical Centre, Faculty of Medicine, University of Freiburg, Robert-Koch-Str. 3, 79106, Freiburg, Germany.,German Cancer Consortium (DKTK) Partner Site Freiburg, German Cancer Research Centre (DKFZ), Heidelberg, Germany
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