Comm Eye Health Vol. 31 No. 101 2018 pp 34. Published online 09 May 2018.

TNM8 classification

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The TNM classification for retinoblastoma, which is developed by the American Joint Committee on Cancer (AJCC), has recently been updated from TNM7 to TNM8. The newest dataset for retinoblastoma from the UK’s Royal College of Pathologists (RCPath), released in early 2018, reflects the changes in the TNM classification.

Definition of primary tumour (cT)

cTX Unknown evidence of intraocular tumour
cT0 No evidence of intraocular tumour
cT1 Intraocular tumour(s) with sub-retinal fluid ≤ 5mm from the base of any tumour
cT1a Tumours ≤ 3mm and further than 1.5 mm from the disc and fovea
cT1b Tumours > 3 mm or closer than 1.5 mm to the disc and fovea
cT2 Intraocular tumour(s) with retinal detachment, vitreous seeding or sub-retinal seeding
cT2a Sub-retinal fluid > 5 mm from the base of any tumour
cT2b Tumours with vitreous seeding and/or sub-retinal seeding
cT3 Advanced intraocular tumour(s)
cT3a Phthisis or pre-phthisis bulbi
cT3b Tumour invasion of the pars plana, ciliary body, lens, zonules, iris or anterior chamber
cT3c Raised intraocular pressure with neovascularization and/or buphthalmos
cT3d Hyphema and/or massive vitreous hemorrhage
cT3e Aseptic orbital cellulitis
cT4 Extraocular tumour(s) involving the orbit, including the optic nerve
cT4a Radiological evidence of retrobulbar optic nerve involvement or thickening of the optic nerve or involvement of the orbital tissues
cT4b Extraocular tumour clinically evident with proptosis and orbital mass

Definition of regional lymph nodes (cN)

cNX Regional lymph nodes cannot be assessed
cN0 No regional lymph nodes involvement
cN1 Evidence of preauricular, submandibular, and cervical lymph node involvement

Definition of distant metastasis (M)

cM0 No signs or symptoms of intracranial or distant metastasis
cM1 Distant metastasis without microscopic confirmation
cM1a Tumour(s) involving any distant site (e.g. bone marrow, liver) on clinical or radiological tests
cM1b Tumour involving the central nervous system on radiological imaging (not including trilateral retinoblastoma)
pM1 Distant metastasis with microscopic confirmation
pM1a Histopathological confirmation of tumour at any distant site (e.g. bone marrow, liver, or other)
pM1b Histopathological confirmation of tumour in the cerebrospinal fluid or CNS parenchyma

Definition of heritable trait (H)

HX Unknown or insufficient evidence of a constitutional RB1 gene mutation
H0 Normal RB1 alleles in blood tested with demonstrated high sensitivity assays
H1 Bilateral retinoblastoma, retinoblastoma with an intracranial CNS midline embryonic tumour (i.e. trilateral retinoblastoma), patient with family history of retinoblastoma, or molecular definition of constitutional RB1 gene mutation