Primary laser therapy as monotherapy for discrete retinoblastoma

Background/aim Laser photocoagulation is less invasive than chemotherapy (systemic, intra-arterial or periocular) and brachytherapy. We studied the safety and efficacy of laser as primary monotherapy for discrete retinoblastoma with well-defined borders and attached retina. Methods A single-institution retrospective non-comparative review (2004-2018) of discrete retinoblastoma tumours managed with primary laser (532 or 810 nm wavelength, 0.5-1 s duration and power titrated until desired tumour whitening). Efficacy was evaluated by tumour long-term stability avoiding non-laser therapies. Safety was evaluated by frequency of laser-related complications and uncontrollable tumour progression. Results Eligible were 112 tumours in 55 eyes of 44 patients. Laser monotherapy (median 2 sessions) achieved initial remission in 95/112 (85%) tumour. Initial encircling only laser photocoagulation was associated with tumour progression (9/11, one tumour had vitreous seeding) compared with direct or combined photocoagulation techniques (0/94 and 0/7 tumours, respectively, p<0.001). Direct laser had no vitreous seeding, haemorrhage or injury to vital structures. Tumour recurrences developed in 52/112 (46%) tumour but repeat laser achieved long-term stability, except five tumour recurrences that required invasive therapy. Receiver operating characteristic analysis identified threshold largest basal diameter of 3 disc diameters (DD) for successful laser monotherapy, where 92/106 (87%) of tumours <= 3 DD and 0/6>3 DD achieved long-term stability with laser monotherapy (p<0.001). Overall, 35/55 (64%) eyes and 24/44 (55%) patients achieved long-term stability with laser monotherapy. No eye was enucleated for uncontrollable tumour progression. Conclusions Discrete retinoblastoma <= 3 DD can be effectively and safely managed with laser monotherapy, sparing a significant proportion of patients/eyes from more invasive therapies.