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Microwave hyperthermia for choroidal melanoma in rabbits
P S Swift1, P R Stauffer, P D Fries
1Department of Radiation Oncology, University of California, San Francisco 94143.
Investigative Ophthalmology & Visual Science
|September 1, 1990
Summary
Hyperthermia combined with radiation therapy shows promise for treating choroidal melanoma, potentially reducing radiation dose and preserving vision. This study found heat alone demonstrated significant tumoricidal effects in an animal model.
Area of Science:
- Ophthalmology
- Oncology
- Medical Physics
Background:
- Radiation therapy offers good local control for choroidal melanoma but often causes visual acuity impairment due to radiation-induced vasculopathy.
- Hyperthermia exhibits a synergistic effect with radiation in human cancers, suggesting potential benefits for ocular melanoma treatment.
Purpose of the Study:
- To investigate the efficacy of hyperthermia as a standalone treatment for choroidal melanoma.
- To evaluate the potential of hyperthermia to reduce radiation dosage requirements in ocular melanoma therapy.
Main Methods:
- A 2450-MHz microwave plaque applicator with cooling was used to deliver hyperthermia to rabbit eyes with choroidal melanomas.
- Thermal mapping was performed, and thermocouple probes monitored tumor temperatures, aiming for 41.0-46.0°C for 1 hour in survival animals.
- Tumor response was assessed via ultrasound and visual examinations over a 1-month follow-up period.
Main Results:
- A 92% tumor response rate was achieved in tumors treated at temperatures exceeding 43.0°C for 1 hour.
- No significant toxicity was observed in the treated rabbit eyes.
- Hyperthermia alone demonstrated notable tumoricidal properties in this animal model.
Conclusions:
- Hyperthermia is a promising therapeutic modality for choroidal melanoma, showing significant tumor reduction with minimal toxicity.
- Further research into hyperthermia, potentially in combination with reduced radiation doses, could improve visual outcomes for choroidal melanoma patients.