Intra-arterial chemotherapy salvages cT3b and cT3c retinoblastoma eyes, but not cT3d

Design

Multicentre retrospective cohort, 11 Chinese tertiary centres

Population

1566 treatment-naive unilateral retinoblastoma eyes (870 cT2, 696 cT3, AJCC 8th edition)

Primary outcome

Globe salvage, with overall and metastasis-free survival and vision-preserving rate

Effect

Salvage HR for intra-arterial vs intravenous chemotherapy 3.65 (95% CI 1.91 to 6.98) in cT3b and 4.02 (2.79 to 5.80) in cT3c; no difference in cT3d; survival unchanged vs primary enucleation

Eleven Chinese tertiary centres pooled 1566 treatment-naive unilateral retinoblastoma eyes staged by the eighth edition AJCC clinical criteria, 870 cT2 and 696 cT3, and compared intra-arterial chemotherapy, intravenous chemotherapy and primary enucleation. Globe salvage was higher with intra-arterial chemotherapy overall, and the effect was concentrated in two subcategories: cT3b eyes, with a hazard ratio for salvage of 3.65 (95% CI 1.91 to 6.98), and cT3c eyes, 4.02 (2.79 to 5.80). In cT3d eyes the two chemotherapy routes did not differ.

What gives the finding weight is what did not change. Overall survival and metastasis-free survival were no different between intra-arterial chemotherapy and primary enucleation, and high-risk histopathological features in eyes that eventually came out were no more common after intra-arterial treatment than after primary enucleation in cT3b and cT3c disease. Vision was not merely cosmetic salvage either: 79.4 per cent of eyes salvaged with intra-arterial chemotherapy retained at least light perception, against 65.0 per cent of those salvaged intravenously.

This is a retrospective cohort, so route was chosen by clinicians rather than allocated, and the healthier eye or the better-resourced family may have found its way to the catheter. Treat it as the best available evidence for a question no one will randomise, not as proof. The practical reading is that advanced unilateral disease short of cT3d deserves a discussion about globe-preserving intra-arterial treatment at a centre that does it regularly, and that cT3d remains an indication to enucleate promptly rather than to try.

• Stage unilateral disease by cT3 subcategory before counselling; the b, c and d distinction is what drove the result.
• Ask whether the treating centre has an established intra-arterial programme, not just access to an interventional suite.
• Record the family's understanding that salvage does not mean useful central vision in every eye.
• Keep the enucleation conversation open for cT3d disease, where delay bought nothing here.
• In Indian practice, weigh the time and cost of repeated visits to a tertiary centre against the salvage chance for that specific eye.

The statistics, in plain English

The hazard ratios here describe globe salvage, so higher is better, and both confidence intervals sit well clear of 1.0 - the benefit is unlikely to be chance. The absence of a survival difference is a null result from a retrospective comparison, which is reassuring rather than conclusive: this design cannot exclude a small survival cost, and it cannot rule out that eyes routed to the catheter were the more favourable ones to begin with.

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