Retinoblastoma Outcomes Based on the 8th Edition American Joint Committee on Cancer Pathological Classification in 1411 Patients.

Purpose: To evaluate the outcomes of retinoblastoma (RB) based on the 8^th edition of the American Joint Committee on Cancer (AJCC) pathological classification in a global cohort of patients.

Design: Retrospective, multicentre, intercontinental collaborative study PARTICIPANTS: 1411 patients INTERVENTION(S): Primary enucleation with/without adjuvant chemotherapy/radiotherapy MAIN OUTCOMES(S): Orbital tumor recurrence, tumor-related metastasis, tumor-related death RESULTS: Based on the 8^th edition AJCC pathological classification, 645 (46%) eyes belonged to pT1, 164 (11%) to pT2, 493 (35%) to pT3, and 109 (8%) to pT4 categories. At a mean follow-up of 38 months (median, 35 months; <1-149 months), orbital tumor recurrence was seen in 8 (1%), 5 (3%), 22 (4%) and 25 (23%) of pT1, pT2, pT3, and pT4 (p<0.001) categories, respectively; tumor-related metastasis was seen in 7 (1%), 5 (3%), 40 (8%), and 46 (43%) of pT1, pT2, pT3, and pT4 (p<0.001) categories, respectively; tumor-related death was seen in 12 (2%), 7 (4%), 64 (13%), and 64 (59%) of pT1, pT2, pT3, and pT4 (p<0.001) categories, respectively. Multivariate Cox proportional hazards analysis of outcomes revealed pT category and adjuvant therapy as independent predictors of outcomes. Categories pT3b (p=0.005), pT3c (p<0.001), pT3d (p<0.001), and pT4 (p<0.001) had a greater hazard for orbital recurrence; categories pT2a (p=0.015), pT3a (p<0.001), pT3b (p<0.001), pT3c (p<0.001), pT3d (p<0.001) and pT4 (p<0.001) had a greater hazard for tumor-related metastasis; and categories pT2a (p=0.068), pT2b (p=0.004), pT3a (p<0.001), pT3b (p<0.001), pT3c (p<0.001), pT3d (p<0.001) and pT4 (p<0.001) had a greater hazard for tumor-related death when compared to the pT1 category. Patients who did not receive adjuvant therapy had greater hazards of orbital tumor recurrence in categories pT3b (p=0.005), pT3c (p=0.003), and pT4 (p=0.002); greater hazards of tumor-related metastasis in categories pT3a (p=0.001), pT3b (p=0.01), pT3c (p=0.001), and pT4 (p=0.007); and tumor-related death in categories pT3a (p<0.001), pT3b (p=0.009), pT3c (p=0.018), and pT4 (p<0.001) when compared to those who received adjuvant therapy.

Conclusion: The 8^th edition AJCC pathological classification predicts outcomes in patients undergoing primary enucleation for RB, and adjuvant therapy is associated with a lower risk of orbital recurrence, tumor-related metastasis, and tumor-related death in the pT3 and pT4 categories.