IO Learning 2020;8:E39-E40. Epub 2020 May 20.
As the field of interventional oncology (IO) grows, interventional radiologists increasingly administer radionuclides. Thus, they must be knowledgeable on aspects of radiation safety that have long been under the domain of nuclear medicine. One area requiring greater understanding is in the handling of contaminated patient remains, especially in the rare case of untimely death. Within IO, this issue is specifically important in patients being treated with Yttrium-90 (Y-90) radioembolization. The purpose of this article is to comment on these issues and recommend discussions regarding these concerns with patients and their families prior to therapy.
Per current practice in the United States, patients receiving Y-90 therapy are releasable into the public with minimal restrictions as the liver and surrounding tissues provide shielding to keep exposure to others below the limit of federal regulations.1 When it comes to handling patient remains, however, there are currently no adequate federal guidelines, and state guidelines vary.
In burial, the body integrity is maintained, providing the same shielding as in living patients. There is also no significant concern for hazardous exposure with the drainage of body fluids in embalming, or with the dissection of the body cavity in autopsies. This is due to the fact that microspheres remain fixed in the hepatic tissue, with no leaching from the Y-90 intrinsic to the glass microspheres, and only minimal leaching demonstrated from the resin microspheres within the first 24 to 48 hours after treatment.2 Indeed, even in a case where there was some measurable activity external to the body of a patient who had passed after previous radioembolization, no detectable radiation was measured in fluids evacuated during the embalming process.3
Cremation, however, violates body tissue integrity, removing this shielding and possibly aerosolizing particles, raising concern for ingestion or inhalation for which there is a lower harmful dose threshold. As cremation has become the most popular method to handle remains in the United States,4 this is a growing potential concern.
In the United States, dated guidelines outline an activity limit for cremation regardless of type of radionuclide administered, ie, not specific to Y-90.5 Thus, another more practical guideline suggesting that radioactive waste can be stored for 10 half-lives (0.05% residual activity) prior to disposal is often applied by radiation safety officers in the setting of cremation.6 In the case of Y-90, which has a half-life of 2.74 days,7 this means waiting approximately 30 days after treatment. Though usually a non-issue with appropriate patient selection, untimely early death from any cause can and does occur. Instead of waiting 30 days, another option would be to explant the liver prior to cremation, which may be necessary in some states regardless of timing;3 however, per radiation safety licensing statutes, explantation would require the decedent’s body to be returned to the treating facility for the procedure. Due to cultural, storage, and transportation concerns, either of these options may present challenges for both families and death-care industry workers.
Of note, other investigations have focused on concerns involving longer-lived contaminants within Y-90 microspheres, chiefly in the glass variant. For background, in the production of Y-90 from stable Y-89, other stable isotopes in the glass also become activated, leading to impurities with half-lives that are much longer than Y-90. These include Y-88 (106.6 days), Y-91 (58.5 days), Eu-154 (8.8 years), Eu-152 (13.6 years), Co-60 (5.3 years), and Co-57 (270.9 days).7 However, the activity levels of these impurities are many orders of magnitude less than the total GBq measured and prescribed for therapy, shown to pose no significantly increased risk to the living patients or their caregivers.7 In terms of aerosolization and exposure to crematory workers, even in the near-impossible scenario of inhalation of an entire 100 mg dose of glass Y-90 microspheres, the estimated dose from the largest contaminant (Y-91 at approximately 6000 Bq7) would be about 4 mrem, or about the same received from a transcontinental flight or one chest x-ray.8 Thus, in cases of cremation within 30 days, it is only exposure to Y-90 itself that is of any concern.
Recently, a patient was cremated 5 days after treatment with intravenous lutetium (Lu)-177 dotatate (half-life = 6.65 days).9 Although the activity of contamination subsequently measured did not pose any risk of hazardous exposure to workers, this event demonstrated that adequate communication between the family and the appropriate authorities could have avoided the public alarm highlighted in subsequent national headlines, and any possibility of harm in a similar future situation.
In our large interventional oncology practice, we have had experiences with patients passing soon after Y-90 treatment, with a family preference for cremation. For example, one event included a patient who passed away in another city and hospital system 13 days after Y-90 radioembolization. Fortunately, the patient’s partner made the other hospital aware of the recent treatment, our radiation safety officer was contacted, and the family was amenable to the request to delay cremation until 30 days post treatment. In a different event, a family had been notified of possible challenges presented by untimely early death prior to treatment, and so when the patient passed away the remains were held in our system until 30 days after treatment prior to cremation. In both cases, it was communication of the presence of radioactive materials by informed and aware family members that averted possible hazardous exposure to crematorium workers.
Additionally, in our practice, radiation safety officers measure the dose rate on contact and at 1 meter from the liver just before the patient leaves for recovery. Using the half-life of Y-90, we can estimate the dose rates at any time to effectively compare these dose rates to background radiation and communicate the radiation risks to outside hospitals, funeral homes, and crematoriums.
Our experiences have prompted regular discussion of plans for handling remains with patients and families during the consent process prior to embarking on therapy to avoid any possible hazardous exposure. In the growing majority of cases where cremation is planned, we advise them of the 30-day “guidance” and let them know to contact us should untimely early death occur.
While better guidelines are needed, the authors suggest that interventional radiologists in practices utilizing these radioactive substances should work with their radiation safety staff to familiarize themselves with the radiation safety concerns of their treatments. Furthermore, we propose that discussions of these concerns should be commonplace in the preprocedural consent processes at all institutions, including any applicable national or state guidelines that may exist. While it is a hopefully uncommon situation, such conversations could help decrease any potentially hazardous exposure to death-care industry workers, or public alarm, in the case of untimely death.
1. U.S. Nuclear Regulatory Commission. Title 10, Code of Federal Regulations §35.75 Release of individuals containing unsealed byproduct material or implants containing byproduct material (2017). Available at https://www.nrc.gov/reading-rm/doc-collections/cfr/part035/part035-0075.html. Accessed May 18, 2020.
2. Grosser O, Ruf J, Pethe A, et al. Urinary excretion of yttrium-90 after radioembolization with yttrium-90-labeled resin-based microspheres. Health Phys. 2018;114:58-63.
3. Nelson K, Vause PE, Koropova P. Post-mortem considerations of yttrium-90 (90Y) microsphere therapy procedures. Health Phys. 2008;95(Suppl 5):S156-S161.
4. National Funeral Directors Association. Cremation and burial report. Brookfield, WI: National Funeral Directors Association, 2017. Available at https://www.nfda.org. Accessed May 18, 2020.
5. International Atomic Energy Agency. Safety reports, series No. 63. Release of patients after radionuclide therapy (2009). Available at https://www.iaea.org/publications/8179/release-of-patients-after-radionuclide-therapy. Accessed May 18, 2020.
6. U.S. Nuclear Regulatory Commission. Title 10, Code of Federal Regulations §35.92(a)(1) Decay-in-storage (2002). Available at https://www.nrc.gov/reading-rm/doc-collections/cfr/part035/part035-0092.html. Accessed May 18, 2020.
7. Metyko J, Williford JM, Erwin W, Poston J, Jimenez S. Long-lived impurities of 90Y-labeled microspheres, TheraSphere and SIR-Spheres, and the impact on patient dose and waste management. Health Phys. 2012;103:S204-S208.
8. Centers for Disease Control and Prevention. Radiation from air travel. Epub 2015 December 07. Available at https://www.cdc.gov/nceh/radiation/air_travel.html. Accessed May 14, 2020.
9. Yu NY, Rule WG, Sio TT, Ashman JB, Nelson KL. Radiation contamination following cremation of a deceased patient treated with a radiopharmaceutical. JAMA. 2019;321:803.
From the Departments of 1Diagnostic Radiology, 2Interventional Radiology, and 3Radiation Safety, Imaging Institute, Cleveland Clinic, Cleveland, Ohio.
The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Martin is on the Interventional Oncology Scientific Advisory Board for Boston Scientific Corporation, has consulted for Terumo Medical, and has served on the Business Strategy Advisory Board for BTG. The remaining authors report no conflicts of interest regarding the content herein.
Address for Correspondence: Gaurav Gadodia, MD, Imaging Institute, Cleveland Clinic, 9500 Euclid Ave, Cleveland, OH 44195. Email: Ggadodia.firstname.lastname@example.org