Abstract
Background: Biology-guided radiotherapy (BgRT) uses real-time functional imaging to guide radiation therapy treatment. Positron emission tomography (PET) tracers targeting prostate-specific membrane antigen (PSMA) are superior for prostate cancer detection than conventional imaging. This study aims at describing nodal and distant metastasis distribution from prostate cancer and at determining the proportion of metastatic lesions suitable for BgRT.
Methods: A single-institution patient subset from the ProPSMA trial (ID ACTRN12617000005358) was analysed. Gross tumour volumes (GTV) were delineated on the CT component of a PSMA PET/CT scan. To determine the suitability of BgRT tracking zones, the normalized SUV (nSUV) was calculated as the ratio of SUVmax inside the GTV to the SUVmean of adjacent three-dimensional shells of thickness 5 mm/10 mm/20 mm as a measure of signal to background contrast. Targets were suitable for BgRT if (1) nSUV was larger than an nSUV threshold and (2) non-tumour tissue inside adjacent shell was free of PET-avid uptake.
Results: Of this cohort of 84 patients, 24 had at least one pelvic node or metastatic site disease, 1 to 13 lesions per patient, with a total of 98 lesions (60 pelvic nodes/38 extra-pelvic nodal diseases and haematogenous metastases). Target volumes ranged from 0.08 to 9.6 cm3 while SUVmax ranged from 2.1 to 55.0. nSUV ranged from 1.9 to 15.7/2.4 to 25.7/2.5 to 34.5 for the 5 mm/10 mm/20 mm shell expansion. Furthermore, 74%/68%/34% of the lesions had nSUV ≥ 3 and were free of PSMA PET uptake inside the GTV outer shell margin expansion of 5 mm/10 mm/20 mm. Adjacent avid organs were another lesion, bladder, bowel, ureter, prostate, and liver.
Conclusions: The majority of PSMA PET/CT-defined radiotherapy targets would be suitable for BgRT by using a 10-mm tracking zone in prostate cancer. A subset of lesions had adjacent non-tumour uptake, mainly due to the proximity of ureter or bladder, and may require exclusion from emission tracking during BgRT.
| Original language | English |
|---|---|
| Article number | 854589 |
| Journal | Frontiers in Oncology |
| Volume | 12 |
| DOIs | |
| Publication status | Published - 12 Apr 2022 |
| Externally published | Yes |
Bibliographical note
Funding Information:This research is partially funded by RefleXion Medical. This work is also funded in part by the Peter MacCallum Cancer Centre Foundation. ProPSMA was an Australian and New Zealand Urogenital and Prostate (ANZUP) Cancer Trial Group co-badged study by a clinical trial grant from the Prostate Cancer Foundation of Australia, funded by Movember. Shankar Siva is supported by the Victorian Cancer Council Colebatch Fellowship. MH is supported by a Challenge Award from the Prostate Cancer Foundation (PCF) supporting the Prostate Cancer Theranostics and Imaging Centre of Excellence (ProsTIC); funding was from Canica AS, Oslo, Norway. The funder was not involved in the study design, collection, analysis, interpretation of data, the writing of this article or the decision to submit it for publication.
Publisher Copyright:
Copyright © 2022 Gaudreault, Chang, Hardcastle, Jackson, Kron, Hanna, Hofman and Siva.
Keywords
- BgRT
- BTZ
- oligometastasis
- prostate
- PSMA
ASJC Scopus subject areas
- Oncology
- Cancer Research
Access to Document
- Utility of Biology-Guided Radiotherapy to De Novo Metastases Diagnosed During Staging of High-Risk Biopsy-Proven Prostate Cancer
Copyright 2022 the authors. This is an open access article published under a Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.