Transpupillary laser thermotherapy of retinoblastoma

Abstract

Introduction. Despite the fact that transpupillary thermotherapy (TTT) is one of the main local methods of small retinoblastoma (RB) destruction, only a few studies have been published on the use of this method, and they are devoted only to certain aspects of the application of TTT.Purpose of the study – to evaluate the effectiveness of TTT in the treatment of children with RB.Material and methods. In the period from 2011 to 2020, 177 children (224 eyes, 1156 tumors) with RB were treated by TTT. Of these, 99 (56 %) patients were boys, 78 (44 %) – girls. The mean age at the time of treatment was 16.8 months (from 0 to 86 months). Bilateral RB was observed in 128 (72.3 %) patients, monolateral – in 49 (27.7 %). In 51 (28.8 %) cases, TTT was performed on an only eye. TTT was performed on eyes that had RB of groups A (n = 43; 19 %), B (n = 81; 36 %), C (n = 31; 14 %), D (n = 63; 28 %), E (n = 6; 3 %). In total, 1156 tumors were treated by TTT. 488 (42 %) tumors were localized post-equatorially (of which 27 were located juxtapapillary, 23 – in the macular zone, 22 – paramacular). 668 (58 %) foci had pre-equatorial localization (on the middle and far periphery of the fundus). The number of foci in one eye varied from 1 to 48 (mean – 5). The mean tumor thickness was 1.1 mm (from 0.2 to 4.5), the mean base diameter was 2.2 mm (from 0.3 to 13.4). TTT was performed using a diode laser with the following parameters: wavelength – 810 nm, spot diameter – 1200 microns, power from 200 to 800 mW (mean – 350 mW), exposure-from 3 to 15 s in the application mode, and continuous in the scanning mode.Results. Complete tumor regression after TTT was achieved in 92 % of cases (1064 tumors). Incomplete regression of the tumor with stabilization was achieved in 0.7 % (8 tumors). The average number of TTT sessions to achieve full regression was 1.7 (from 1 to 10). Complete tumor regression after 1 TTT session was achieved in 54 % of cases (622 tumors), after 2 sessions – in 11 % (132 tumors), after 3 sessions – in 7 % (85 tumors), after 4 or more sessions– in 19 % (225 tumors). In 7 % of cases (82 tumors), due to the progression of the tumor, other treatment methods (brachytherapy, cryotherapy, stereotactic radiosurgery) were applied. 209 (93 %) eyes were preserved. 15 (7 %) eyes were enucleated due to continued tumor growth, total retinal detachment, vitreous hemorrhage, or subatrophy of the eyeball. The mean follow-up after TTT was 35.5 months (from 3 to 112 months).Conclusion. TTT is a highly effective method of RB treatment and can be used for destruction of small primary foci of both post-equatorial and pre-equatorial localization, residual tumors after inefficiency of other local methods. TTT is also effective in the treatment of large cavitary tumors located in functionally significant areas of the retina.