Explore the results from a recent study that found that an 18F-NaF PET scan could help identify patients with bone metastases from castration-resistant prostate cancer who would be most likely to respond to treatment with radium-223.
Radium-223 is an alpha-emitting radionuclide used to treat patients with bone metastases from castration-resistant prostate cancer (CRPC). It’s a type of internal radiotherapy treatment that targets bone cancer cells, and it’s been shown to improve overall survival, quality of life, and time to skeletal events.
Given these impacts, it’s essential to correctly identify which patients may benefit most from this treatment. And according to a recent study published in European Radiology, an imaging technique called an 18F-sodium fluoride (18F-NaF) PET scan might be able to help us do just that.
How the Study Was Designed
The study, led by researchers from the Royal Marsden and the Institute of Cancer Research, involved analyzing 133 lesions in 36 patients with CRPC that metastasized only to the bones using the following two methods: whole-body MRI with diffusion-weighted imaging and PET scans with 18F-NaF and 18F-choline.
Whole-body MRI with diffusion-weighted imaging is a proven technique used to observe changes in apparent diffusion coefficient, indicating the movement of water molecules in tissue. This technique was performed at the study’s onset and every eight weeks throughout.
The second method involved carrying out PET scans with 18F-NaF and 18F-choline. The researchers chose this method because it’s well known that radium-223 has been shown to be more effective in areas with a high bone turnover rate. This turnover rate increases when cancer cells in the bones release proteins that interfere with healthy bone cells. As a result, the cells that break down bone are overactivated.
And since 18F-NaF has a similar structure to calcium, the researchers wanted to evaluate whether higher concentrations of this marker could be found in bones with a high turnover rate, theoretically revealing where radium-223 is most likely to be successful.
What the Study Found
After utilizing these two different methods, the researchers found that 18F-NaF uptake by metastases at baseline was significantly higher in patients whose apparent diffusion coefficient increased by at least 30 percent over the course of the study, as measured by the whole-body MRI with diffusion-weighted imaging technique. This indicates that a higher concentration of 18F-NaF identified using a PET scan before treatment begins is associated with a better response to treatment with radium-223.
The researchers also found that there was no correlation between 18F-choline uptake and treatment response.
How These Findings Align with Other Studies
Based on these findings, the researchers concluded that 18F-NaF PET could be used to identify the patients who would be most likely to respond to treatment with radium-223.
But this isn’t the first revealing study in this space.
In another study, led by researchers from the Royal Marsden and the Institute of Cancer Research, it was found that diffusion-weighted MRI can be used to assess a patient’s response to treatment with radium-223. These findings are especially critical because unlike other tumors that will shrink if treatment is effective, bone metastases will not. And so in order to assess a patient’s response to treatment, clinicians have to consider a patient’s survival and overall quality of life.
Based on this unmet need in CRPC care, the findings from these two studies could help enhance the use of personalized approaches in the treatment of this patient population.
References:
Flux GDD. Imaging and dosimetry for radium-223: The potential for personalized treatment. The British journal of radiology. August 2017. Accessed December 28, 2023. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5858794/.
Keizman D, Fosboel M, Reichegger H, et al. Imaging response during therapy with radium-223 for castration-resistant prostate cancer with bone metastases-analysis of an international Multicenter Database. PubMed. Accessed December 28, 2023. https://pubmed.ncbi.nlm.nih.gov/28244493/.
Parker C, Tunariu N, Tovey H, et al. Radium-223 in metastatic castration-resistant prostate cancer: whole-body diffusion-weighted magnetic resonance imaging scanning to assess response. Oxford Academic. October 3, 2023. Accessed December 28, 2023. https://academic.oup.com/jncics/article/7/6/pkad077/7288180?login=false.
Radium 223 (Xofigo) for metastatic prostate cancer. Cancer Research UK. July 27, 2022. Accessed December 28, 2023. https://www.cancerresearchuk.org/about-cancer/prostate-cancer/metastatic-cancer/treatment/radiotherapy/radium-223.
Scientists now able to predict response to radium-223 treatment in prostate cancer bone metastases. Medical Xpress. December 21, 2023. Accessed December 28, 2023. https://medicalxpress.com/news/2023-12-scientists-response-radium-treatment-prostate.html.
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