Central Nervous System
PV QA 2 - Poster Viewing Q&A 2
MO_2_2502 - Ocular Brachytherapy for Intra-ocular Melanoma: Experience and Outcomes in The Province of Alberta
Monday, October 22
10:45 AM - 12:15 PM
Location: Innovation Hub, Exhibit Hall 3
Ocular Brachytherapy for Intra-ocular Melanoma: Experience and Outcomes in The Province of Alberta
D. Dinakaran1,2, M. Larocque1, R. Kelsey2, P. Grewal2, S. Lapere2, A. D. Murtha1, and E. Weis2; 1Cross Cancer Institute, Edmonton, AB, Canada, 2University of Alberta, Edmonton, AB, Canada
Uveal melanoma is the most common cause of intra-ocular malignancy, and accounts for about 5% of melanoma diagnoses. It has a 12 year overall survival approaching 60%, and disease specific mortality ranging from 17% to 21%. Treatment historically was only through surgical enucleation, which conferred morbidity from vision loss, pain, cosmetic and social stigma. A multicenter randomized control trial by the Collaborative Ocular Melanoma Study (COMS) has found no difference in survival between enucleation versus organ preserving ocular brachytherapy for up to 12 years follow-up. This has become the preferred option to spare most of the morbidities of enucleation.
We perform a first look of Alberta’s experience and outcomes with its ocular brachytherapy program since its inception in 2011.
174 patients from Alberta and the western Canada catchment area with intra-ocular melanoma and no evidence of distant metastasis were treated between 2011 and 2017 and followed from time of diagnosis. All patients had ocular ultrasound and CT staging as minimum investigations. Treatment was done with temporary ocular brachytherapy at the Cross Cancer Institute with I-125 high dose seeds (4.14 mCi average activity) mounted in COMS plaque or Eye Physics-brand (Los Alamitos, CA, USA) plaque. Dose calculations were performed using Plaque Simulator (Los Alamitos, CA, USA) treatment planning software, correcting for plaque heterogeneities. All implants and explants were done as day procedures, with general anesthesia for implant and sedation for explants. Implant time ranged from 4 days to 7 days. All cases were prescribed 70 Gy to a prescription point located 0.5 mm beyond the tumour apex. Plaque size, location, and seed loading pattern were chosen to ensure 100% coverage of a margin 2 mm beyond the tumour base, and to minimize OAR doses (fovea, nerve) as much as possible. Analysis was carried out using cox regression stratified for survival by Gene Expression Profiling (GEP) class and the tumour’s Largest Base Diameter (LBD), measuring time from treatment to development of metastasis.
Median follow-up to for our cohort was 2.9 years. Median dose achieved was 70.4Gy. There were 20 cases of disease failure by way of metastatic disease, with no local failures and no post-brachy enucleations. Median time to failure was not reached for GEP class 1a and 1b versus 4.1 years for class 2 (p=0.001). Median time to failure for patients with LBD <12mm was not reached versus 6.8 years for LBD >=12mm (p<0.001). Most metastases were to the liver with some patients salvaged with metastatectomy or SBRT.
Ocular brachytherapy for uveal melanoma provides excellent local control with disease free survival that is comparable to surgical enucleation. In the Alberta setting, it continues to be a logistically feasible and effective organ-sparing approach to treating intra-ocular malignancy.
Author Disclosure: D. Dinakaran: None. M. Larocque: None. R. Kelsey: None. E. Weis: None.