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Radium-induced eye melanomas in dogs
G N Taylor1, R D Lloyd, S C Miller
1Radiobiology Division 2334 CAMT, Salt Lake City, UT 84108-1218, USA. glen.taylor@hsc.utah.edu
Health Physics
|July 26, 2000
Summary
Radium isotopes (226Ra and 228Ra) injected into beagles caused intraocular melanomas, primarily in the ciliary body. These tumors, originating from pigment epithelium, differ from neural crest-derived melanomas and have not been observed in humans.
Area of Science:
- Ophthalmology
- Radiology
- Oncology
Background:
- Intravenous administration of radium isotopes (226Ra and 228Ra) can lead to significant tissue retention.
- Intraocular structures, particularly pigmented tissues, are susceptible to radiation damage.
Purpose of the Study:
- To investigate the intraocular radiotoxicity of intravenously injected radium isotopes.
- To characterize the development and origin of radium-induced intraocular tumors in beagles.
Main Methods:
- Beagle dogs were intravenously administered 226Ra and 228Ra.
- Ocular tissues were examined for retention of radium and development of lesions.
- Tumor origin and characteristics were histopathologically analyzed.
Main Results:
- Approximately 0.071% of injected radium was retained in each eye.
- Radium accumulated in the tapetum and pigmented structures, causing lesions like melanotic plaques and melanosis.
- Intraocular melanomas developed, predominantly in the ciliary body, arising from the pigment epithelium.
Conclusions:
- Radium isotopes induce intraocular melanomas in beagles, distinct from neural crest-derived melanomas.
- These findings add to the known radium-induced neoplasms, including bone cancer.
- Radium-induced intraocular melanomas have not been reported in humans.