Classification systems provide ‘robust’ stratification of advanced retinoblastoma
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GENEVA — Two new classification systems allow for improved stratification of patients with retinoblastoma, according to study results presented at World Cancer Congress.
This improves the ability to predict presence of high-risk pathology, as well as risk for death due to metastatic disease, Ankit Singh Tomar, MBBS, MD, clinical research fellow at New York Eye Cancer Center, and colleagues concluded.
Retinoblastoma — the most common type of eye cancer among children — accounts for approximately 2% of childhood cancers.
An estimated 200 to 300 children in the United States are diagnosed with retinoblastoma each year, according to American Cancer Society.
More than 90% of these children are cured. However, outcomes are considerably poorer for those whose disease has spread beyond the eye, and advanced retinoblastoma is the most common presenting stage in developing countries.
Clinicians typically use clinical features to choose between primary enucleation or globe-salvage. However, existing classification systems do not adequately predict risk for metastatic disease at presentation or provide insights that can guide treatment choices, according to study background.
Tomar and colleagues assessed whether clinical features and tumor size of advanced intraocular retinoblastoma as defined by the 8th Edition of American Joint Committee on Cancer (AJCC) Staging for Retinoblastoma provides statistically significant medical evidence for high-risk pathology. They also evaluated whether these criteria could help predict risk for death due to metastatic disease.
Researchers conducted a retrospective registry-based analysis of 2,190 patients treated between 2001 and 2013 at 18 ophthalmic oncology centers in 13 countries.
Investigators used clinical features outlined in AJCC staging categories cT2 and cT3 to define advanced retinoblastoma.
They also incorporated new AJCC-Ophthalmic Oncology Task Force (OOTF) tumor size groups, defined as:
• Group 1: less than 50% of globe volume involved;
• Group 2: more than 50% but less than two-thirds of globe volume involved;
• Group 3: more than two-thirds of globe volume involved; and
• Group 4: diffuse infiltrating retinoblastoma.
The most common treatments included primary enucleation, systemic chemotherapy with secondary enucleation, and systemic chemotherapy with eye salvage.
Risk for death due to metastatic disease increased with increasing cT subcategory and AJCC-OOTF size group (P < .001 for both), according to Kaplan-Meier cumulative survival estimates.
Cox proportional hazards regression analysis revealed higher risk for mortality due to metastatic disease among patients with categories cT3c (glaucoma), cT3d (intraocular hemorrhage) and cT3e (orbital cellulitis) than those in category cT2a. Results also showed higher risk for mortality due to metastatic disease among those in AJCC-OOTF Group 3 and Group 4 disease than those in Group 1.
Slightly less than half (43%; n = 942) of patients in the analysis underwent primary enucleation. Approximately one-third (30%) of those patients had high-risk pathology.
High-risk pathology appeared significantly associated with cT subcategories and AJCC-OOTF size groups (P < .001 for both).
“Both AJCC-UICC [retinoblastoma] staging clinical cT3 subcategories and AJCC-OOTF size groups provided a robust stratification of clinical risk for the presence of high-risk pathology and, therefore, the risk [for] metastatic death,” Tomar and colleagues wrote. “Primary enucleation offered the highest survival rates for patients with advanced intraocular retinoblastoma.”
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Tomar AS, et al. Abstract 76. Presented at: World Cancer Congress; Oct. 18-20, 2022; Geneva.
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