title: Low-dose radiation from 18F-FDG PET does not increase cancer frequency or shorten latency but reduces kidney disease in cancer-prone Trp53+/- mice.
abstract: There is considerable interest in the health effects associated with low-level radiation exposure from medical imaging procedures. Concerns in the medical community that increased radiation exposure from imaging procedures may increase cancer risk among patients are confounded by research showing that low-dose radiation exposure can extend lifespan by increasing the latency period of some types of cancer. The most commonly used radiopharmaceutical for positron emission tomography (PET) scans is 2-[(18)F] fluoro-2-deoxy-d-glucose ((18)F-FDG), which exposes tissue to a low-dose, mixed radiation quality: 634 keV β+ and 511 keV γ-rays. The goal of this research was to investigate how modification of cancer risk associated with exposure to low-dose ionising radiation in cancer-prone Trp53+/- mice is influenced by radiation quality from PET. At 7-8 weeks of age, Trp53+/- female mice were exposed to one of five treatments: 0 Gy, 10 mGy γ-rays, 10 mGy (18)F-FDG, 4 Gy γ-rays, 10 mGy (18)F-FDG + 4 Gy γ-rays (n > 185 per group). The large 4-Gy radiation dose significantly reduced the lifespan by shortening the latency period of cancer and significantly increasing the number of mice with malignancies, compared with unirradiated controls. The 10 mGy γ-rays and 10 mGy PET doses did not significantly modify the frequency or latency period of cancer relative to unirradiated mice. Similarly, the PET scan administered prior to a large 4-Gy dose did not significantly modify the latency or frequency of cancer relative to mice receiving a dose of only 4 Gy. The relative biological effectiveness of radiation quality from (18)F-FDG, with respect to malignancy, is approximately 1. However; when non-cancer endpoints were studied, it was found that the 10-mGy PET group had a significant reduction in kidney lesions (P < 0.021), indicating that a higher absorbed dose (20 ± 0.13 mGy), relative to the whole-body average, which occurs in specific tissues, may not be detrimental.
authors.affiliation: Department of Medical Physics and Applied Radiation Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada and Department of Nuclear Medicine, McMaster University Medical Centre, 1200 Main Street West, Hamilton, Ontario L8N 3Z5, Canada.
authors.forename: Kristina
authors.initials: K
authors.lastname: Taylor
authors.affiliation: Department of Medical Physics and Applied Radiation Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada and lemonja@mcmaster.ca.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Lemon
authors.affiliation: Department of Medical Physics and Applied Radiation Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada and.
authors.forename: Nghi
authors.initials: N
authors.lastname: Phan
authors.affiliation: Department of Medical Physics and Applied Radiation Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada and.
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Boreham
mesh_terms: D000818:Animals; D004307:Dose-Response Relationship, Radiation; D019788:Fluorodeoxyglucose F18; D005720:Gamma Rays; D007674:Kidney Diseases / Q000000981:diagnostic imaging*; D008223:Lymphoma / Q000000981:diagnostic imaging / Q000473:pathology; D008297:Male; D051379:Mice; D009369:Neoplasms / Q000000981:diagnostic imaging*; D009928:Organ Specificity; D012516:Osteosarcoma / Q000000981:diagnostic imaging / Q000473:pathology; D049268:Positron-Emission Tomography; D016019:Survival Analysis; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D016159:Tumor Suppressor Protein p53; D019788:Fluorodeoxyglucose F18