Study of the Efficacy of Indocyanine Green Enhanced Transpupillary Thermotherapy as a Treatment Modality for Retinoblastoma

Abstract

Background Retinoblastoma represents approximately 4% of all pediatric malignancies and is the most common ocular malignancy in children. It has one of the highest survival rates among all pediatric malignancies owing to improving treatment methods over the years. Objectives The purpose of our work was to evaluate the efficacy of intravenous indocyanine green dye injection combined with diode laser transpupillary thermotherapy (TTT) as a treatment modality for Group (B) intraocular retinoblastoma compared to the standard protocol of treatment. Patients and Methods A prospective interventional comparative study was conducted in the Ocular Oncology Clinic, Ophthalmic Department, Ain Shams University Hospital in the period from August 2017 to December 2020. The study was conducted on twenty tumors, classified as Group (B) retinoblastoma according to International Classification of Intraocular Retinoblastoma (ICRB). It includes; Tumors >3 mm (in basal dimension or thickness), tumors located in the macula (≤3 mm to foveola), juxta-papillary tumors (≤1.5 mm to disc) or tumors surrounded by subretinal fluid (≤5 mm from the tumor margin). They were divided into two main groups: Group I: It included ten (10) tumors; newly diagnosed or recurrent. This group was treated with systemic chemotherapy plus ICG enhanced diode laser TTT, Group II (control group): It included ten (10) tumors; newly diagnosed or recurrent. This group was treated with systemic chemotherapy plus conventional diode laser TTT. Results The study found that ICG has significantly improved uptake of diode laser, eliminating the need for increasing the laser power to the photocoagulation levels which would disrupt the inner retinal layers. ICG-TTT allowed rapid tumor regression and decreased the number of laser sessions needed to achieve tumor regression.ICG-TTT was successful with 3 challenging recurrent masses on a hypopigmented scar and achieved complete regression. There was no statistically significant difference between the two groups as regards the disease-free survival curves using Kaplan Meier analysis. During the period of post chemotherapy follow up, 3 tumors in Group I (30%) and 2 tumors in group II (20%) developed recurrence. And one case in group I (10%) developed a new mass in a remote site. Conclusion The study concluded that ICG-TTT is both efficient and safe despite some potential complications.