Abstract
Purpose :
The International Classification System for Retinoblastoma has become the standard method for diagnosing intraocular retinoblastoma. However, there are currently discrepancies in some aspects of the system, particularly when classifying advanced cases (i.e. Groups D and E). The goal of this study was to analyze the impact of a large tumor size criteria for classifying advanced intraocular retinoblastoma on rates of globe salvage and high-risk histopathologic features.
Methods :
A retrospective chart review was conducted of 212 eyes diagnosed with Group D (111 eyes) or Group E (101 eyes) retinoblastoma in at least one eye from January 1, 2006 to December 31, 2016 using the Los Angeles (LA) Classification System (no size criteria for Group E). The 111 Group D tumors were then reclassified to Group E using 10, 12, 14, 16, and 18 mm tumor size criteria as determined by ultrasound or MRI.
Results :
For eyes in the original LA classification, 66.7% of Group D and 10.5% of Group E eyes which underwent globe preservation therapy with either systemic or intra-arterial chemotherapy avoided enucleation or radiotherapy (p<0.0001) (median follow-up of 33.0 months); 8.5% of Group D enucleated globes had high-risk histopathologic features while 26.3% of Group E globes had high risk features (p=0.0065). When Group D eyes with tumors meeting the size criteria were reclassified to Group E, 65.7-74.4% of Group D eyes and 16.1-36.7% of Group E eyes avoided enucleation or radiotherapy. Applying the tumor size criteria, 0-10.9% of Group D eyes had high-risk features.
Conclusions :
Our retrospective analysis suggests that a large tumor size criteria for Group E retinoblastoma does not have significant clinical basis, given that the LA classification system provided the greatest separation in globe salvage rates between Group D and E eyes. The LA classification system also showed a statistically significant difference in the rates of high-risk features between Group D and E eyes. To avoid discrepancies in the literature, we recommend that centers use one uniform system for classifying advanced intraocular retinoblastoma.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.