Abstract
Purpose: :
To evaluate a case series of patients treated with slotted eye plaques for choroidal melanomas within 1.0 mm or surrounding the optic disc.
Methods: :
Retrospective, single-center study of 24 patients, treated between 1995 and January 2010. Recorded characteristics were related to the patient, tumor, ultrasonography, and outcomes. Follow-up data included change in visual acuity, tumor-size, recurrence, eye-retention and metastasis. All cases were treated with plaques containing 8-mm wide variable depth slots. Prescription doses ranged from 69.3-163.8 Gy (mean 85.0 Gy) based on delivering a minimum 85 Gy tumor dose to the tumor within the slot. All treatments were continuously delivered over a 5-7 day duration.
Results: :
Mean patient age at presentation was 55 years (median: 53, range: 22-83 years). The tumors were within 1.0 mm of the optic nerve in 12.5% (n=3), juxtapapillary (touching up to 180 degrees of the optic disc) in 21% (n=5), greater or equal to 180 degress in 25% (n=6), circumpapillary (surrounding 360 degrees of the optic disc) in 37.5% (n=9), and there was no view in 1 patient (4%). Ultrasound revealed dome-shaped tumors in 83%, collar button in 17%, and 8% (n=2) with intraneural invasion. Mean tumor thickness was 3.4 mm (SD±1.7, median: 2.8, range: 1.4 to 7.1). Mean largest basal dimension was 10.8 mm (SD± 3.4, median: 11.4, range: 4.6-16.4).Initial visual acuities were median 20/25 (range 20/20 to NLP) and decreased to median 20/40 (range 20/20 to NLP) with a mean follow up of 25 months (range: 4-60). Twelve patients required periodic intravitreal bevacizumab to suppress their radiation optic neuropathy. This study revealed a 100% local control rate for the 21 patients where slotted plaque brachytherapy was used as primary treatment. One of the 3 patients treated for failure of conventional plaque irradiation also failed slotted plaque and was the only secondary enucleation. None have developed metastasis during the study interval.
Conclusions: :
Finger’s slotted plaque radiation therapy can be used to control juxtapapilary and circumpapillary choroidal melanomas. Incorporating the optic nerve (within the plaque) allows for more posterior placement and inclusion of the entire tumor beneath the plaque and within the targeted zone. These 5-year results suggest slotted plaques offer better local control than notched plaque designs, and offer an alternative (to proton beam or enucleation) for circumpapillary melanoma..
Keywords: melanoma • optic nerve • radiation therapy