International Journal of Radiation Oncology*Biology*Physics
Clinical Investigation106Ruthenium Brachytherapy for Retinoblastoma
Introduction
Brachytherapy was introduced by Moore et al. (1) who used radon seeds to treat choroidal melanoma in 1930, and retinoblastoma 1 year later (2). In 1948, Stallard (3) introduced 60Co plaque radiotherapy for choroidal melanoma, which risked exposing personnel to relatively high radiation doses. Lower energy brachytherapy emerged later, both gamma-ray–emitting 125I in the United States (4) and β-ray–emitting 106Ru in Europe (5) improved radiation safety for patients and therapists. 106Ru and 125I plaques (properties presented in Table 1) allowed for a reduced dose delivery to normal ocular structures and greater irradiation to the tumor base. Over the years, brachytherapy proved to be an efficient treatment for several intraocular tumors, offering an alternative to enucleation and external beam radiotherapy. Furthermore, repeat plaque therapy can be performed on a single eye without the deleterious effects caused by repetitive external beam radiotherapy. In the United States, 125I has gained wide acceptance and represented the principal brachytherapy source used for the treatment of melanoma in the Collaborative Ocular Melanoma Study (6) and for other intraocular tumors by major centers 7, 8, 9, 10, 11. In Europe, although 125I is also widely used, 106Ru remains the isotope of choice because of the reduced radiation to critical eye structures such as the lens, macula, and optic disc compared with 125I 12, 13, 14, 15, 16, 17, 18. This has been attributed to the different radiation dose distributions of the two isotopes because 106Ru has limited lateral irradiation. 106Ru plaques have been limited to the treatment of tumors <5 mm 14, 17, 19, 20 based on the assumption that 125I has a greater penetration of the surface dose compared with 106Ru.
Retinoblastoma is the most frequent intraocular tumor of childhood, threatening patients' lives and visual function (20). Plaque radiotherapy has become a treatment option in primary and secondary treatment of retinoblastoma with the use of both 125I and 106Ru. However, only a few studies have been published on the use of 106Ru for retinoblastoma 14, 19, and the investigators did not make any distinction among primary, secondary, or salvage treatment.
To determine the effectiveness of 106Ru plaques for the treatment of retinoblastoma, we reviewed the results of consecutive retinoblastoma patients treated at the Jules-Gonin Eye Hospital during a 14-year period.
Section snippets
Methods and Materials
The tenets of the Helsinki Declaration were followed, and institutional ethical committee approval for outcomes analysis was not required. Patients gave oral consent for data collection.
Results
Between October 1992 and July 2006, 65 tumors were treated with 106Ru plaques. Of the 65 tumors, 63 in 41 eyes of 39 patients were included in this study, after exclusion of two tumors retreated by 106Ru brachytherapy. Fourteen patients had multiple plaque treatments. The percentage of each type of 106Ru plaque applied is listed in Table 2. The clinical features of patients and tumors and the radiation characteristics are listed in Table 3. Table 4 presents the different categories of treatment
Discussion
Modern management of retinoblastoma includes focal treatment modalities such as cryocoagulation or thermotherapy 22, 23, which are effective for tumors <4 mm in diameter without vitreous seeding and/or peritumoral retinal detachment. Brachytherapy is a widely used focal treatment that avoids the significant complications related to external beam radiotherapy, including periorbital tissue damage, bone deformity, and associated second cancers 24, 25, 26, 27. Brachytherapy is delivered within
Conclusion
We used 106Ru brachytherapy for 63 retinoblastomas in 39 patients. Tumor control was achieved in 59–73% of the cases at 12 months, with a mean tumor apex dose of 55.3 Gy. Eye retention was achieved in 31 (76%) of 41 eyes. 106Ru brachytherapy was effective in treating retinoblastoma as primary, secondary, and salvage treatment, when other modalities had failed to control the tumor. Within a treatment limit of a tumor height of 6 mm, tailored for the 106Ru plaques, tumor size was not a predictive
Aknowledgments
We warmly thank Doris Hadjistilianou, M.D. for patients' referral and Sue Houghton for precious collaboration in data collection.
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Cited by (0)
Presented in part at the American Academy of Ophthalmology Annual Meeting, New Orleans, LA, November 2007.
Conflict of interest: none.