Newer treatment approaches for retinoblastoma have improved rates of globe preservation. This has opened the question of whether preserving the globe renders patients at high risk for metastases. This study endeavored to pinpoint the clinical features in enucleated eyes with advanced retinoblastoma that could predict high-risk pathologic features.
Study design
This international, multicenter, retrospective study was performed in collaboration with 18 retinoblastoma centers in 13 countries. The researchers reviewed the medical records of all patients diagnosed with retinoblastoma from January 5, 2001, to December 31, 2013, identifying 942 eyes with cT2 and cT3 categories of advanced retinoblastoma that had undergone primary enucleation. The data was anonymized and entered into an online database. The study definitions were based on the 8th edition of the American Joint Committee on Cancer’s (AJCC) TNMH (tumor, node, metastasis, heredity) retinoblastoma staging system.
Outcomes
Of 942 eyes, 282 (30%) had high-risk features on pathologic examination (massive choroidal invasion, retrolaminar invasion of optic nerve head not involving the transected end of the nerve, scleral invasion, and extraocular invasion by tumor). Compared to cT2a eyes (subretinal fluid >5 mm from the base of any tumor), cT3c (iris neovascularization with glaucoma, odds ratio of 2.3), cT3d (intraocular hemorrhage, odds ratio of 2.5), and cT3e (aseptic orbital cellulitis, odds ratio of 3.3) eyes predicted the presence of high-risk pathologic features. Compared with size group 1 (<50% of globe volume occupied by tumor), size group 3 (more than two-thirds of globe volume occupied by tumor, odds ratio of 3.3) and size group 4 (diffuse infiltrative retinoblastoma, odds ratio of 4.1) were strongly associated with high-risk pathologic features.
Limitations
This study is based on information extracted from the patients’ medical records that were then entered into the study’s database, producing results with the limitations of all retrospective studies. Moreover, the patients were managed in 18 different centers by different ocular oncologists raising the possibility of differences in examination techniques and documentation of findings. As mentioned by the authors, their registry database did not include any field for pars plana or ciliary body involvement and this may account for the low number of cT3b eyes in the study.
Clinical significance
The presence of high-risk pathologic features in eyes with retinoblastoma is associated with higher rates of orbital tumor recurrence and systemic metastasis. Currently, many eyes with retinoblastoma, even in relatively advanced stages, are conservatively treated without enucleation. Moreover, prior chemotherapy can change the pathological picture and prevent the detection of high-risk pathological features. The findings of this study allow ocular oncologists to use clinical features in place of pathological features when such pathological information is not available or not reliable.