Comm Eye Health Vol. 31 No. 101 2018 pp 11-13. Published online 19 May 2018.
Lead Clinician for Ophthalmology and Retinoblastoma Services: Royal London Hospital, London, UK.
Retinoblastoma Service: Royal London Hospital; Ocular Oncology Service NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK.
Classifying and staging retinoblastoma is an essential first step when planning how to manage a child with the condition; it also gives important information about prognosis.
Classification schemes in cancer are mainly used to compare the results of different treatments and to enable a prognosis to be given.
If retinoblastoma is left untreated, it will extend beyond the eye. Unfortunately, this is the type most commonly seen in low- and middle-income countries. The tumour can penetrate the globe wall and be visible in and around the eye. It can also reach the central nervous system via the optic nerve, or it can spread to other parts of the body via the blood stream (metastases).
In 2006, Chantada and colleagues developed the International Retinoblastoma Staging System (IRSS; Table 1).1 It sub-classifies the disease from stage O–IV. Stage O is intraocular disease, usually having a good outcome with treatment, and stage IV is retinoblastoma with metastases, which has a poor prognosis.
The IIRC scheme groups tumours from A-E, depending on their size, location, and additional features,including the presence of retinoblastoma ‘seeds’ (small colonies of cancerous cells in the vitreous) and/or retinal detachment.
For eyes in groups A–C: the globe could be salvaged in ≥90% of eyes.
For eyes in group D: the globe could be salvaged in 47% of eyes.
Group E eyes underwent primary enucleation and were excluded from analysis.
Both the IIRC and ICRB classification systems (see Table 2, overleaf) are now used as the main classification schemes for intraocular retinoblastoma and serve clinicians and researchers across the world.4 The images in Figure 1 correspond to each category.
Another classification system that is used for all cancer types, including retinoblastoma, was created by the American Joint Committee on Cancer (AJCC). The TNM scheme classifies cancer according to involvement of the primary site: tumour (T), lymph nodes (N) and presence of systemic metastasis (M). The recently published 8th edition includes a hereditary (H) component for Rb, making it the cTNMH scheme (c for clinical). The cTNMH categories are based on whether the tumour burden is determined to be intraretinal, intraocular, advanced intraocular or extraocular.7 The TNM scheme also has a pathological (pTNM) sub-classification which is widely used by ophthalmic pathologists. Read this article online to see the full scheme: www.cehjournal.org.
Classification and staging systems for retinoblastoma have evolved as new treatments became available. Several schemes are currently available. For disease confined to the globe, the IIRC, ICRB and cTNMH systems are available, along with additional classifications describing vitreous seeds. For extraocular disease, the IRSS and cTNMH schemes can be used.
2 Linn Murphree A. Intraocular retinoblastoma: the case for a new group classification. Ophthalmic Clin North Am 2005;18:41–53.
3 Shields CL, Mashayekhi A, Au AK, et al. The International Classification of Retinoblastoma Predicts Chemoreduction Success. Ophthalmology 2006;113:2276– 2280.
5 Munier FL, Gaillard MC, Balmer A, Soliman S, Podinsky G, Moulin AP, et al. Intravitreal chemotherapy for vitreous disease in retinoblastoma revisited: from prohibition to conditional indications. Br J Ophthalmic 2012;96:1078–1083.
6 Berry JL, Bechtold M, Shah S, Zolfaghari E, Reid M, Jubran R, Kim JW. Not all seeds are created equal: seed classification is predictive of outcomes in retinoblastoma. Ophthalmology 2017;124:1817– 1825.
7. Mallipatna AC, Gallie BL, Chévez-Barrios P, Lumbroso-Le Rouic L, Chantada G, Doz F, Munier FL, et al. In: Amin MB, Edge SB, Greene FL, et al., eds. AJCC Cancer Staging Manual. 8th ed. New York: Springer; 2017.