Abstract
Purpose :
To review long-term outcomes of the University of Southern California Plaque Simulator (PS) software and Eye Physics (EP) plaques. PS incorporates fundus photography, B-scan ultrasonography, and CT or MRI for 3-dimensional modeling to build custom plaques and guide intraoperative plaque localization. We hypothesize that PS/EP has the advantage of delivering lower doses to critical ocular structures, resulting in lower rates of radiation toxicity and improved visual outcomes compared to Collaborative Ocular Melanoma Study (COMS) plaques, while maintaining equal local tumor control.
Methods :
A retrospective review of 134 patients treated for choroidal melanoma with iodine 125 brachytherapy, using PS software and EP plaques, from 1990 through 2015. A dose of 85 Gy was prescribed to the tumor apex over 7 days. Primary outcomes were local tumor recurrence, enucleation for any reason, and metastasis. Secondary outcomes were visual acuity change and complications of radiation.
Results :
Median follow up was 42 months. We achieved a Kaplan-Meier estimated 98.3% tumor control and 96.4% globe salvage at 5 years (Figure 1), and 88.3% survival without metastases at 5 years. Median dose to the tumor apex was 85.0 Gy; median doses to the macula, optic nerve, and lens were 39.5, 30.3, and 12.3 Gy, respectively. Radiation retinopathy was seen in 43% of patients, optic neuropathy in 19%, and cataracts in 47%. 37% of patients lost ≥6 Snellen lines of vision.
Conclusions :
The PS/EP system has the potential to decrease radiation to surrounding ocular structures by more accurately conforming to tumors, creating a steep dose gradient outside of the tumor (Figure 2). We achieved rates of local tumor control, enucleation, and metastases comparable to those of COMS. We report lower median doses to the macula, optic nerve, and lens than COMS, as well as lower rates of radiation retinopathy, optic neuropathy, cataracts, and significant vision loss. Overall, PS 3D planning software and custom EP plaques result in excellent tumor control, and can improve long-term visual and radiation-related outcomes after brachytherapy.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.