ML25084A215
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| ML25084A215 | |
| Person / Time | |
|---|---|
| Issue date: | 04/07/2025 |
| From: | Harvey R NRC/NMSS/DMSST |
| To: | |
| References | |
| Download: ML25084A215 (14) | |
Text
Review of Yttrium-90 (Y-90)
Microsphere Gastrointestinal (GI) Deposition Subcommittee Presented by Richard P. Harvey, Subcommittee Chair Advisory Committee on the Medical Use of Isotopes April 7, 2025
Subcommittee Members
- John Angle, MD (Consultant)
- Joanna Fair, MD
- Michael Folkert, MD
- Richard Harvey, DrPH (Chair)
- Michael OHara, PhD
- Zoubir Ouhib, MS
- NRC Staff Resource: Sarah Spence, CHP
Subcommittee Charge
- Evaluate changes in Y-90 microsphere brachytherapy practice and recent Y-90 microsphere medical events to identify potential cause of sudden increase in reported events involving unexpected GI deposition.
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Background===
- Y-90 microsphere brachytherapy has been performed for approximately 20 years using Sir-Spheres (resin) or Theraspheres (glass). Sirtex and Boston Scientific are the current respective manufacturers.
- Five events have been reported to NRCs Medical Event Database (NMED) since May 2024 indicating significant deposition of Y-90 microspheres to the gastrointestinal (GI) system with one event being retracted.
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Background===
- GI deposition is a known undesirable outcome associated with microsphere brachytherapy but the NRC typically receives very few reported medical events with GI deposition.
- The aforementioned 5 events involved Theraspheres but similar events have occurred with Sir-Spheres historically.
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Background===
- Prior to Y-90 microsphere treatment, a mapping procedure with Tc-99m macroaggregated albumin (MAA) is performed to predict microsphere flow dynamics and deposition in the liver
- Mapping may be performed same day or ahead of time
- Timing and site of MAA injection are not standardized
- Acceptable duration of time between mapping and treatment is variable based on AU experience and judgement
Findings
- Incidence rate of <0.5% for Y-90 microsphere brachytherapy medical events as reported to NMED
- Incidence rate has remained unchanged with a minor increase in events with GI deposition in 2024 (unclear if this represents a trend)
- Volume of treatments is increasing (manufacturer data to NRC)
Findings 0
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5 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025
Findings
- Improved imaging technology may have resulted in more events identified - increased use of Single Photon Emission Computed Tomography (SPECT) vs. planar imaging or lack of post-therapy imaging
- Treatments are challenging due to the difficulty of placing catheters in small vessels with tortuous paths
- Difficult to standardize process because of patient-specific anatomy, normal variants and clinical judgement/expertise
Licensee Explanations for GI Deposition
- Difference in microsphere (treatment) size vs. Tc-99m MAA (mapping) size - unlikely to be clinically relevant
- Mapping & treatment same day or not - licenses perform via both methods with success
- Pharmaceuticals such as Avastin may affect the flow dynamics of MAA or Y-90 microspheres - these agents are or should not be taken for several weeks prior to treatment
Subcommittee Recommendations to NRC
- NRC should determine the number of procedures being performed by leveraging relationships with manufacturers to provide a better understanding of medical events as it relates to Y-90 procedure volume
- No apparent consistent cause for these events has been identified but continued monitoring is recommended
- NRC should consider methods to inform licensees of these events
Recommendations for Industry Consideration
- Licensees should perform post-therapy imaging to determine the extent and impact of GI deposition
- Tc-99m MAA, particularly SPECT/CT imaging, in combination with careful pre-procedure angiography, are useful in screening for potential GI deposition
Recommendations for Industry Consideration
- Manufacturers should provide additional education and training for Authorized Users
- Pitfalls
- Recommendations
- Concerns regarding using catheters other than recommended by manufacturer
- Maintain documentation of additional provided education
- Manufacturers should make every effort to inform in writing their users about any unexpected medical events with recommendations as a preventive measure to avoid a possible trend
- ACMUI - Advisory Committee on the Medical Use of Isotopes
- AU - Authorized User
- CHP - Certified Health Physicist
- GI - Gastrointestinal Deposition
- MAA - Macroaggregated Albumin
- NMED - NRC Medical Event Database
- NRC - United States Nuclear Regulatory Commission
- SPECT - Single Photon Emission Computed Tomography
- Tc-99m - Technetium-99m