Episcleral brachytherapy for retinoblastoma

Iodine-125 Plaque Radiotherapy for Retinoblastoma Recurrence Following Intra-arterial Chemotherapy

PURPOSE

To assess the efficacy and toxicity of Iodine-125 (I-125) plaque radiotherapy for retinoblastoma following intra-arterial chemotherapy (IAC).

METHODS

Clinical records of patients with retinoblastoma who received I-125 plaque radiotherapy after IAC at the Ocular Oncology Service at Wills Eye Hospital between December 1, 2009 and April 30, 2020, were retrospectively reviewed.

RESULTS

Forty-one retinoblastomas in 41 eyes of 41 patients were treated with I-125 plaque radiotherapy after IAC at a median age of 32 months. The indication for plaque radiotherapy was solid tumor recurrence with or without overlying subretinal/vitreous seeds (n = 33, 80%), subretinal seeds alone (n = 6, 15%), and vitreous seeds alone (n = 2, 5%). The median irradiated basal diameter and thickness was 9 and 4 mm, respectively. Mean radiation dose to tumor apex was 3,483 centigray (cGy) delivered at mean rate of 35 cGy/hr. The irradiated site was controlled in 39 eyes (95%) at a median of 20 months after plaque radiotherapy for solid tumor (31 of 33, 94%), subretinal (6 of 6,100%), and vitreous seeds (2 of 2, 100%). A subgroup of tumors occurring within an ischemic retinal/choroidal field was identified on fluorescein angiography (n = 24) and demonstrated control in 22 of 24 (92%). Using Kaplan-Meier analysis, radiation complications at 2 years included vitreous hemorrhage (37%), retinopathy (28%), papillopathy (18%), and cataract (18%). Five eyes (12%) were enucleated for recurrence outside the irradiated area, chronic vitreous hemorrhage, and/or total retinal detachment.

CONCLUSIONS

Iodine-125 plaque radiotherapy provided 95% control for retinoblastoma tumors that failed IAC, including those in ischemic fields untreatable with further chemotherapy. Radiation complications should be anticipated in eyes exposed to substantial chemotherapy. [J Pediatr Ophthalmol Strabismus. 2022;59(3):164-171.].

Combination of Brachytherapy and Intravitreal Chemotherapy in the Treatment of Retinoblastoma with Vitreous Seeding

Purpose

The aim of this study was to report the efficacy of combined intravitreal chemotherapy (IVC) and ruthenium-106 brachytherapy in retinoblastoma, either as first-line or second-line treatment, following systemic chemoreduction or intra-arterial chemotherapy.

Methods

Retrospective data of 18 eyes from 18 patients treated with IVC and brachytherapy from August 2014 to December 2019 were collected.

Results

The method described was our first-line therapy in 6 patients, whereas it was used as second-line treatment after chemoreduction in the remaining 12 patients. The eyes showed the following classification at initial presentation: 2 group B eyes, 3 group C eyes, and 13 group D eyes. The mean follow-up was 19.5 months (range 2-53 months). The mean patient age at brachytherapy was 34.0 months (range 15-83 months). The median prescribed dose at the tumour base and apex was 574.5 ± 306.7 Gy and 88.5 ± 12.2 Gy, respectively. The ocular retention rate was 66.7%. Six eyes had to be enucleated due to uncontrollable subretinal and recurrent vitreous seeding, tumour relapse, recurrence of a solid tumour elsewhere in the eye, and persistent vitreous bleeding with loss of tumour control. The mean number of intravitreal injections of melphalan was 5.0. Two patients received a simultaneous injection of topotecan for insufficient therapeutic response. With regard to radiogenic complications, we could observe temporary retinal and vitreous bleeding (27.8%), serous retinal detachment (44.4%), and radiogenic maculopathy and retinopathy (11.1%). None of the children showed metastatic disease during follow-up.

Conclusion

Ruthenium-106 plaque therapy in combination with IVC is an effective local therapy with good tumour control rates even in advanced eyes. Overall, the analysed therapeutic approach shows an acceptable side-effect profile, especially when considering that external-beam radiation therapy and systemic polychemotherapy or at least the number of cycles needed, with their increased incidence of adverse events, can thus be avoided.

Retinoblastoma and vision

The assessment of vision has a growing importance in the management of retinoblastoma in the era of globe-conserving therapy, both prior to and after treatment. As survival rates approach 98-99% and globe salvage rates reach ever-higher levels, it is important to provide families with information regarding the visual outcomes of different treatments. We present an overview of the role of vision in determining the treatment given and the impact of complications of treatment. We also discuss screening and treatment strategies that can be used to maximise vision.

Intravenous Chemotherapy for Retinoblastoma in the Era of Intravitreal Chemotherapy: A Systematic Review

Purpose

The published data on ocular survival following intravenous chemotherapy of retinoblastoma (RB) seems to be skewed by evolving practice patterns induced by use of intravitreal chemotherapy (iVitc). We aimed to explore potential role of iVitc for vitreous seeding for patients treated with intravenous chemotherapy (IVC).

Methods

A literature search was performed to identify cases of RB treated with primary IVC prior to advent of iVitc by various search engines (PubMed, Medline, and Google) from 1992 to 2018. Studies were excluded if number of cases were less than 40 or lacked data related to type of recurrence and its treatment. Rates and patterns of recurrence and its management were categorized.

Results

Out of 15 studies identified, only 10 studies (797 eyes) met the inclusion criteria. The mean age at presentation was 15.3 months (range 0-192.8 months). Unilateral cases represented 25% of the cohort. The ocular survival rate with primary IVC was 63% (500/797 eyes). Of the 297 eyes (37%) that failed IVC therapy, additional 99 eyes could be salvaged with EBRT (599/797 eyes, 75%). Remaining 198 eyes were enucleated (198/797 eyes 25%). K-M survival analysis could not be done due lack of sufficient data. Recurrences that occurred (mean 12.2 months) after completion of primary IVC included relapse of retinal tumor (143 eyes [48%]), vitreous seeding (73 eyes [25%]), subretinal seeding (49 eyes [16%]), or any combination (103 eyes [35%]). Out of 73 eyes with vitreous seeding, additional 66 eyes (90%) would have been salvaged with iVitc, potentially improving ocular survival rates to 71% (500 + 66/797).

Conclusions

Evolving practice patterns of RB treatment have unfavorably skewed published ocular survival rates following IVC. With incorporation of iVitc, the ocular survival rates with IVC can be potentially improved to be non-inferior to those achieved with intra-arterial chemotherapy.

Retinoblastoma in twins: Risk assessment of genotypic variants

Purpose

To describe methods of risk assessment in twins with retinoblastoma (RB).

Methods

A case series of four RB probands with a twin sibling. Family status, clinical presentation, and RB1 germline status-based risk assessment were analyzed.

Results

Two pairs had a positive family history (unilateral and bilateral RB in one of the parents (#1 and #2, respectively) and two pairs (#3 and #4) were sporadic. One of the familial twins (#1) had a high risk (90%) of manifesting RB in the twin. The other case (#2) with an absent RB1 germline mutation in the twin had a 0% risk of developing RB. Among sporadic cases of twins (#3), genetic testing did not identify a germline mutation (tumor sample unavailable) in the proband which downgraded the risk of germline mutation from 15% to <1%. The twin never developed RB (5 years of age at last follow-up). Pathogenic mosaicism for germline RB1 mutation (c.1723C>T) could be identified (tumor tissue available) in the proband (# 4). Identical germline mutation (and RB tumor) was also noted in the twin. In each case, there was concordance between the assessed risk and manifestation of RB.

Conclusion

Assessment of risk of RB in a twin presents with a unique challenge. Depending upon the genotype variant, the risk of developing RB can vary from 0% to 90%. In addition to family history, clinical manifestation in the proband, zygosity status, and RB1 germline status are critical in formulating risk-appropriate surveillance guidelines.

MRI and dual-energy CT fusion anatomic imaging in Ru-106 ophthalmic brachytherapy

PURPOSE

Brachytherapy with Ru-106 is widely used for the treatment of intraocular tumors, and its efficacy depends on the accuracy of radioactive plaque placement. Ru-106 plaques are MRI incompatible and create severe metal artifacts on conventional CT scans. Dual-energy CT scans (DECT) may be used to suppress such artifacts. This study examines the possibility of creating fusion images from MRI scans (preoperatively) and DECT scans (with the plaque in place) as a tool for confirming the anatomic accuracy of plaque placement.

METHODS AND MATERIALS

Six patients with intraocular lesions (5 with choroidal melanoma and 1 with a retinal vasoproliferative lesion) were included. Fusion images of preoperative MRI scans and DECT scans with the plaque in place were created with the Demo version of the ImFusion suite (ImFusion GmbH, Munchen Germany). Clearance margins between the tumor and plaque edge in axial, transverse, and coronal planes as well as the elevation of the posterior plaque edge from the sclera were recorded and associated with the location of the lesion.

RESULTS

Plaque-tumor clearance margins for transverse, sagittal, and coronal planes were higher for anteriorly located lesions (5.13 mm ± 0.11 [5.0-5.2], 5.10 mm ± 0.26 [4.9-5.4], and 5.33 mm ± 0.45 [4.9-5.8] respectively) than for posteriorly located lesions (4.16 mm ± 1.44 [2.5-5.1], 4.13 mm ± 1.42 [2.5-5.1], and 4.2 mm ± 1.21 [2.8-5.0], respectively). The elevation of the posterior plaque edge from the sclera was 0.33 mm ± 0.28 [0-0.5] and 0.63 mm ± 0.60 [0.7-1.2] for posterior and anterior lesions, respectively.

CONCLUSIONS

Fusion images between DECT and MRI scans may be used as a tool to confirm the accuracy of Ru-106 plaque placement in relation with the intraocular tumors in ophthalmic brachytherapy.

Applications of iodine-125 plaque radiotherapy for residual or recurrent retinoblastoma

OBJECTIVE

To determine the role of iodine-125 plaque radiotherapy (IPR) as a secondary treatment for localized (solitary or multiple) residual (partially regressed) or recurrent (regrowth after ≥6 months stability) retinoblastoma in the era of systemic and/or regional chemotherapy.

DESIGN

A single-institute retrospective, noncomparative, interventional case series managed between July 2014 and June 2019.

PARTICIPANTS

Thirteen consecutive eyes of 12 patients with 14 residual or recurrent retinoblastoma tumors treated with IPR. Patients who had to follow up <1 year post-IPR were excluded except for those who had enucleation.

METHODS

Data collected included pre-IPR treatments, tumor characteristics at IPR, and post-IPR anatomical outcome (local tumor control and globe salvage) and functional outcome (radiation complications).

RESULTS

Local tumor control was achievable in 12 of 14 tumors. Local recurrences were observed in 2 of 5 tumors that exhibited fish-flesh regression after IPR (p = 0.04). Globe salvage was possible in 11 eyes (12 tumors). Only 2 eyes were legally blind and the remaining 9 eyes had vision >20/125. Radiation-induced complications included radiation retinopathy (4/11), radiation papillopathy (1/11), diffuse vitreous hemorrhage (4/11). Eyes with fish-flesh-regressed tumours tended to show more complications, but were statistically insignificant (p = 0.09, Fisher exact test). There was no association of time to IPR (early <6 months vs late >6 months) with occurrence of tumor recurrence or complications (p > 0.05).

CONCLUSION

IPR offers satisfactory local tumor control and globe salvage in localized recurrent/residual retinoblastoma. Fish-flesh tumor regression after IPR should be closely monitored for further recurrences.

[Retinoblastoma]

Retinoblastomas represent 6% of all malignant tumors in children under 5 years old, which untreated lead to blindness in the affected eye and death due to metastases. The main symptoms are leukocoria and strabismus, which if possible, always necessitate a clarification within 1 week for exclusion of a retinoblastoma. The most frequent differential diagnoses are Coats' disease and persistent fetal vasculature (PFV) as well as other intraocular tumors, in particular astrocytomas. Systemic chemotherapy, if necessary in combination with laser hyperthermia, local chemotherapy and brachytherapy are the most important methods for eye-preserving treatment. Advanced cases mostly necessitate enucleation.