Brachytherapy for retinoblastoma: a 13 year experience

Abstract

Brachytherapy (BT) is a method of radiation therapy with radioactive source contacting the tumor. It was proposed by P. Moore and H. Stallard in 1929. Despite those 50 years of experience with the use of BT in ophthalmic oncology, there are only a few studies on the use of Ru-106 BT for retinoblastoma (RB), and no publications on the use of Sr-90 BT have been found.Purpose. To present our own experience with the use of ruthenium and strontium ophthalmic applicators for BT in retinoblastoma.Materials and methods. 120 patients (137 eyes and 194 RB foci) received BT as a local treatment in the period from 2007 to 2020. At the time of treatment the age of the patients varied from 4 to 109 months (mean age 26 months). In 32% of cases (44 eyes) there were monofocal lesions, and in 68% of cases (93 eyes) — multifocal. In 36 cases (30%) BT was performed in the single eye. 79 patients (87 eyes) were treated with the use of ruthenium ophthalmic applicators (OAs), 25 patients (26 eyes) — with the use of strontium OAs, and for the treatment of 16 patients (24 eyes) both ruthenium and strontium OAs were used.Results. Clinically complete tumor regression was achieved in 62 % of cases (120 foci), partial tumor regression — in 31% of cases (60 foci). In 6% of cases (12 foci) continuous tumor growth was observed, and tumor recurrence occurred in 1% of cases (2 foci) within 4 to 6 months after BT. Local tumor control was achieved in 93% of cases.The single eyes were preserved in 92% of cases. BT complications of different intensity were reported in 38% of cases (46 patients — 49 eyes) with the mean follow-up duration of 55 months (3 to 157 months). In 92 % of cases (42 patients — 45 eyes) complications were associated with the use of ruthenium OAs, and only in 8% of cases (4 patients — 4 eyes) — with the use of strontium OAs. Risk factors for radiation-induced complications were identified: focus size (height more than 2.5 mm [P =0.0005], extension more than 7.3 mm [P <0,0001]), sclera dose more than 626 Gr (P = 0,0002), and the central localization of the tumor (P <0.0001).Conclusions. Ruthenium-106 and strontium-90 brachytherapy is a highly effective treatment modality for the management of RB.