Radium-223 in metastatic castration-resistant prostate cancer: whole-body diffusion-weighted magnetic resonance imaging scanning to assess response

Parker, Chris, Tunariu, Nina, Tovey, Holly, Alonzi, Roberto, Blackledge, Matthew D, Cook, Gary J R, Chua, Sue, Du, Yong, Hafeez, Shaista, Murray, Iain, Padhani, Anwar R, Staffurth, John ORCID: https://orcid.org/0000-0002-7834-3172, Tree, Alison, Stidwill, Helen, Finch, Jessica, Curcean, Andra, Chatfield, Peter, Perry, Sophie, Koh, Dow-Mu and Hall, Emma 2023. Radium-223 in metastatic castration-resistant prostate cancer: whole-body diffusion-weighted magnetic resonance imaging scanning to assess response. JNCI Cancer Spectrum 7 (6) , pkad077. 10.1093/jncics/pkad077

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Abstract

Background Radium-223 is a bone-seeking, ɑ-emitting radionuclide used to treat men with bone metastases from castration-resistant prostate cancer. Sclerotic bone lesions cannot be evaluated using Response Evaluation Criteria in Solid Tumors. Therefore, imaging response biomarkers are needed. Methods We conducted a phase 2 randomized trial to assess disease response to radium-223. Men with metastatic castration-resistant prostate cancer and bone metastases were randomly allocated to 55 or 88 kBq/kg radium-223 every 4 weeks for 6 cycles. Whole-body diffusion-weighted magnetic resonance imaging (DWI) was performed at baseline, at cycles 2 and 4, and after treatment. The primary endpoint was defined as a 30% increase in global median apparent diffusion coefficient. Results Disease response on DWI was seen in 14 of 36 evaluable patients (39%; 95% confidence interval = 23% to 56%), with marked interpatient and intrapatient heterogeneity of response. There was an association between prostate-specific antigen response and MRI response (odds ratio = 18.5, 95% confidence interval = 1.32 to 258, P = .013). Mean administered activity of radium-223 per cycle was not associated with global MRI response (P = .216) but was associated with DWI response using a 5-target-lesion evaluation (P = .007). In 26 of 36 (72%) patients, new bone metastases, not present at baseline, were seen on DWI scans during radium-223 treatment. Conclusions DWI is useful for assessment of disease response in bone. Response to radium-223 is heterogeneous, both between patients and between different metastases in the same patient. New bone metastases appear during radium-223 treatment.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Medicine
Publisher:	Oxford University Press
ISSN:	2515-5091
Date of First Compliant Deposit:	14 July 2025
Date of Acceptance:	17 July 2023
Last Modified:	18 Jul 2025 11:45
URI:	https://orca.cardiff.ac.uk/id/eprint/179805

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