Abstract
The use of radionuclide therapy in the clinical setting is expected to increase significantly over the next decade. There is an important need to understand the radiation-induced second cancer risk associated with these procedures. In this study the radiation-induced cancer risk in five radionuclide therapy patients was investigated. These patients underwent serial SPECT imaging scans following injection as part of a clinical trial testing the efficacy of a 131 Iodine-labeled radiopharmaceutical. Using these datasets the committed absorbed doses to multiple sensitive structures were calculated using RAPID, which is a novel Monte Carlo-based 3D dosimetry platform developed for personalized dosimetry. The excess relative risk (ERR) for radiation-induced cancer in these structures was then derived from these dose estimates following the recommendations set forth in the BEIR VII report. The radiation-induced leukemia ERR was highest among all sites considered reaching a maximum value of approximately 4.5. The radiation-induced cancer risk in the kidneys, liver and spleen ranged between 0.3 and 1.3. The lifetime attributable risks (LARs) were also calculated, which ranged from 30 to 1700 cancers per 100,000 persons and were highest for leukemia and the liver for both males and females followed by radiation-induced spleen and kidney cancer. The risks associated with radionuclide therapy are similar to the risk associated with external beam radiation therapy.
Highlights
Radionuclide therapy is a form of therapy involving the systemic administration of a radioactive compound in a patient
There are clear differences between absorbed doses by RAPID using patient-specific Monte Carlo (MC) simulations and OLINDA where these differences can be attributed to the aforementioned weaknesses of the OLINDA software
One would expect similar variations in the excess relative risk (ERR) values calculated for these patients using absorbed dose values from these two sources
Summary
Radionuclide therapy is a form of therapy involving the systemic administration of a radioactive compound in a patient. While the risk of second cancer development from external beam radiation therapy (EBRT) has been investigated extensively [1,2,3], less is known about the radiation-induced cancer risk from radionuclide therapy. Because this risk is largely dependent on the absorbed dose and dose rate in the body one would expect sizeable differences in the risk predictions between these two treatments. The absorbed dose distribution resulting from radionuclide therapy is often heterogeneously distributed throughout the body of the patient unlike the absorbed dose from EBRT that falls off rapidly as a function of distance from the tumor. It is impossible to relate the risks between these treatment options without accounting for these aforementioned differences
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