A Multicenter, International Collaborative Study for AJCC-Staging of Retinoblastoma: Treatment Success and Globe Salvage.

PURPOSE To evaluate the ability of the 8th edition of the American Joint Committee on Cancer (AJCC) Staging to predict local tumor control and globe salvage for children with retinoblastoma (RB). DESIGN International, multicenter, registry-based retrospective case series PARTICIPANTS: 2854 eyes of 2097 patients from 18 ophthalmic oncology centers from 13 countries over 6 continents. METHODS International, multicenter, registry-based data was pooled from patients enrolled between January 2001-December 2013. All RB eyes with adequate records to allow tumor staging by the AJCC 8th edition criteria and follow-up to ascertain treatment outcomes were included. MAIN OUTCOME MEASURES Globe-salvage rates were estimated by AJCC clinical(cTNMH) categories and tumor laterality. Local treatment failure was defined as use of enucleation or external beam radiation therapy (EBRT), with or without plaque brachytherapy or intra-arterial chemotherapy (IAC). RESULTS Unilateral RB occurred in 1340 (47%) eyes. Amongst the 2854 eyes, tumor categories were cT1-cT4 in 696 (24%), 1334 (47%), 802 (28%), and 22 (1%) eyes, respectively. Of these, 1275 (45%) eyes were salvaged, and 1179 (41%) and 400 (14%) underwent primary and secondary enucleation, respectively. The 2- and 5-year Kaplan-Meier cumulative globe-salvage rates without use of EBRT by cTNMH categories were 97% and 96% for category cT1a tumors, 94% and 88% for cT1b tumors, 68% and 60% for cT2a tumors, 66% and 57% for cT2b tumors, and 32% and 25% for cT3 tumors respectively. Risk of local treatment failure increased with increasing cT category (p <0.001). Cox proportional hazards regression analysis confirmed a higher risk of local treatment failure in category cT1b (hazard ratio [HR], 3.5; p=0.004), cT2a (HR, 15.1; p< 0.001), cT2b (HR, 16.4; p< 0.001) and cT3 (HR, 45.0; p< 0.001) compared to category cT1a. Use of plaque brachytherapy and IAC improved local tumor control in categories cT1a (p=0.031) and cT1b (p< 0.001). CONCLUSION Multicenter, international, internet-based data sharing validated the 8th edition AJCC RB staging to predict globe-salvage in a large, real life, heterogenous, real-world retinoblastoma patient population.