Evaluation of globe-preserving therapies in unilateral cT2/cT3 retinoblastoma: a multicentre study of 1566 eyes.

AIMS: To evaluate survival, globe salvage and visual outcomes of globe-preserving treatment approaches in unilateral cT2 and cT3 retinoblastoma, with a focus on cT3 disease. METHODS: This multicentre, retrospective cohort study enrolled 1566 treatment-naïve unilateral retinoblastoma eyes (870 clinical (c)T2, 696 cT3 by eighth American Joint Committee on Cancer clinical tumour, node, metastases staging) from 11 Chinese tertiary centres. Patients underwent intra-arterial chemotherapy, intravenous chemotherapy or primary enucleation. Outcomes were globe salvage, overall survival, metastasis-free survival, high-risk histopathological feature prevalence and vision-preserving rate (≥light perception (LP)). RESULTS: In this multicentre cohort of 1566 eyes, the globe-salvage rate across cT2 and cT3 retinoblastoma was higher with intra-arterial chemotherapy than with intravenous chemotherapy. When stratified by cT3 subcategories, intra-arterial chemotherapy achieved significantly higher globe-salvage rates than intravenous chemotherapy in cT3b eyes (HR 3.65; 95% CI 1.91 to 6.98) and cT3c eyes (HR 4.02; 95% CI 2.79 to 5.80). In contrast, globe salvage did not differ between intra-arterial chemotherapy and intravenous chemotherapy in cT3d eyes. Overall survival and metastasis-free survival did not differ between intra-arterial chemotherapy and primary enucleation. Among eyes with cT3b or cT3c disease, 79.4% of eyes salvaged with intra-arterial chemotherapy and 65.0% of eyes salvaged with intravenous chemotherapy retained at least LP. Detected high-risk pathological features were not significantly different between eyes treated with intra-arterial chemotherapy and those undergoing primary enucleation in cT3b or cT3c disease. Among secondary enucleated eyes with cT3d disease, intra-arterial chemotherapy was associated with lower rates of choroidal invasion. CONCLUSION: Intra-arterial chemotherapy may enable globe salvage in cT3b/c retinoblastoma, whereas cT3d eyes continue to warrant prompt enucleation.