106Ruthenium Plaque Therapy (RPT) for Retinoblastoma

High-Dose-Rate Yttrium-90 (90Y) Episcleral Plaque Brachytherapy for Iris and Iridociliary Melanoma

Purpose

To describe a pilot study on the use of single-session, high-dose-rate, Food and Drug Administration-cleared, yttrium-90 (Y90) plaque brachytherapy for iris and iridociliary melanoma.

Design

A single-center, clinical case series.

Participants

Six consecutive patients were included in this study. Each was diagnosed with an iris or iridociliary melanoma based on clinical examination with or without biopsy.

Methods

Each tumor was staged according to the American Joint Committee on Cancer criteria and received Y90 eye plaque brachytherapy. The main variables were tumor size, patient age, sex, and method of diagnosis (clinical or biopsy). Surgical techniques, treatment durations, and ocular side effects were recorded. Local control was defined as a lack of tumor growth or regression determined by clinical examinations, including slit-lamp and gonio photography, as well as high-frequency ultrasound measurements. Toxicity parameters included acute and short-term corneal/scleral change, anterior segment inflammation, and cataract progression.

Main Outcome Measures

Local and systemic cancer control, tumor regression, visual acuity, as well as radiation-related normal tissue toxicity.

Results

High-dose-rate Y90 plaque brachytherapy was used to treat small (American Joint Committee on Cancer cT1) category melanomas. Single-surgery high-dose-rate irradiations were performed under anesthesia. Because of short treatment durations, high-dose-rate Y90 did not require the additional procedures used for low-dose-rate plaque (e.g., sutures, amniotic membrane epicorneal buffering, Gunderson flaps, and second surgeries for plaque removal). Only conjunctival recession was used to avoid normal tissue irradiation. High-dose-rate Y90 treatment durations averaged 8.8 minutes (median, 7.9; range, 5.8-12.9). High-dose-rate Y90 brachytherapy was associated with no periorbital, corneal (Descemet folds), or conjunctival edema. There was no acute or short-term anterior uveitis, secondary cataract, scleropathy, radiation retinopathy, maculopathy, or optic neuropathy. The follow-up was a mean of 16.0 (range 12-24) months. Evidence of local control included a lack of expansion of tumor borders (n = 6, 100%), darkening with or without atrophy of the tumor surface (n = 5/6, 83%), and a mean 24.5% reduction in ultrasonographically measured tumor thickness. There were no cases of metastatic disease.

Conclusions

High-dose-rate Y90 brachytherapy allowed for single-surgery, minimally invasive, outpatient irradiation of iris and iridociliary melanomas.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

First clinical implementation of Yttrium-90 Disc Brachytherapy after FDA clearance

PURPOSE

Herein, we study if high-dose-rate (HDR) yttrium-90 (⁹⁰Y) brachytherapy could be utilized by medical physicists, radiation oncologists, and ophthalmic surgeons.

METHODS AND MATERIALS

Yttrium-90 (⁹⁰Y) beta-emitting brachytherapy sources received United States Food and Drug Administration clearance for episcleral treatment of ocular tumors and benign growths. Dose calibration traceable to the National Institute of Standards and Technology as well as treatment planning and target delineation methods were established. Single-use systems included a ⁹⁰Y-disc affixed within specialized, multifunction, handheld applicator. Low-dose-rate to high-dose-rate prescription conversions and depth-dose determinations were performed. Radiation safety was evaluated based on live exposure rates during assembly and surgeries. Clinical data for radiation safety, treatment tolerability, and local control was collected.

RESULTS

Practice parameters for the medical physicist, radiation oncologist, and ophthalmic surgeon were defined. Device sterilizations, calibrations, assemblies, surgical methods, and disposals were reproducible and effective. Treated tumors included iris melanoma, iridociliary melanoma, choroidal melanoma, and a locally invasive squamous carcinoma. Mean calculated ⁹⁰Y disc activity was 14.33 mCi (range 8.8-16.6), prescription dose 27.8 Gy (range 22-30), delivered to depth of 2.3 mm (range 1.6-2.6), at treatment durations of 420 s (7.0 min, range 219 s-773 s). Both insertion and removal were performed during one surgical session. After surgery, each disc-applicator- system was contained for decay in storage. Treatments were well-tolerated.

CONCLUSIONS

HDR ⁹⁰Y episcleral brachytherapy devices were created, implementation methods developed, and treatments performed on 6 patients. Treatments were single-surgery, rapid, and well-tolerated with short-term follow up.

Safety and efficacy of indigenously developed Ruthenium-106 eye plaque for brachytherapy of a spectrum of ocular tumors: A case series

ABSTRACT

Various treatment modalities are available for treatment of ocular tumors, which include chemotherapy, laser, and radiotherapy (external beam radiation therapy or brachytherapy). Brachytherapy using plaque applicator is preferred over external beam radiation therapy when the tumor is well localized, as this therapy delivers radiation dose to the tumor with lower doses to normal tissues in the vicinity. However, plaque therapy is expensive and beyond the reach of many poor patients in India. The Bhabha Atomic Research Center (BARC) recently introduced an indigenous Ruthenium-106 plaque to make brachytherapy treatment available and affordable to all needy patients in India. In the present case series, we report our experience using the indigenous Ru-106 plaque for the treatment of a spectrum of ocular tumors.

Ruthenium plaque radiotherapy in the current era of retinoblastoma treatment

BACKGROUND

Two major treatment modalities for retinoblastoma, intraarterial chemotherapy (IAC) and intravitreal chemotherapy (IVitC), have superseded external beam radiotherapy for eye salvage. In this new setting our objectives were to evaluate the indications for plaque radiotherapy, complications, and recurrence rates.

METHODS

Retrospective detailed review of patient's charts was performed for all subjects treated with plaque radiotherapy for retinoblastoma between January 2015 and December 2020.

RESULTS

A total of 12 eyes of 12 patients were included. Mean age at plaque insertion was 45 months (median 29, range 17-150). The treatment dose was 40 Gy to the tumor apex. The indication for plaque radiotherapy was salvage therapy in 11 eyes (92%) and primary treatment in one eye (8%). At last follow-up from plaque insertion (mean 36 months, range 3-67), four (33%) patients had visual acuity better than 0.5 LogMAR and four (33%) had visual acuity worse than 1.0 LogMAR. Radiation-related complications were: one (8%) vitreous haemorrhage, two (16%) non-proliferative radiation retinopathy and one (8%) cataract. Recurrence was detected in four (33%) patients at a mean of 7.8 months (median 5, range 1-20) post-plaque. Globe salvage rate was 75%, as three eyes required enucleation, one to treat recurrence of the tumor treated with plaque and two to treat recurrence of other tumors.

CONCLUSIONS

In the current era of retinoblastoma management, a role for plaque radiotherapy remains for salvage or primary treatment in eyes with localised active tumor, providing tumor control in 66%. Close observation is recommended to both detect recurrence and radiation-related complications.

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.

INTRAVITREAL ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR FOR THE MANAGEMENT OF NEOVASCULARIZATION IN RETINOBLASTOMA AFTER INTRAVENOUS AND/OR INTRAARTERIAL CHEMOTHERAPY: Long-Term Outcomes in a Series of 35 Eyes

PURPOSE

To report the use of anti-vascular endothelial growth factor in the management of retinoblastoma.

METHODS

Retrospective review of 35 eyes (33 patients) treated with at least one intravitreal anti-vascular endothelial growth factor (ranibizumab and/or aflibercept) for new iris (n = 26) and/or retinal neovascularization (n = 21) after intravenous chemotherapy and/or intraarterial chemotherapy.

RESULTS

Most eyes (n = 31/35, 89%) were Group D or E. Previous treatments were salvage intraarterial chemotherapy after intravenous chemotherapy (n = 21/35, 60%), first-line intraarterial chemotherapy (n = 7/35, 20%), and first-line intravenous chemotherapy (n = 7/35, 20%). Associated clinical features were retinal ischemia (94%), retinal detachment (51%), active tumor (34%), intravitreal hemorrhage (43%), and/or glaucoma (17%). Mean 1.6 anti-vascular endothelial growth factor injections/eye were given; 28 eyes received ranibizumab, 2 aflibercept, and 5 both agents. Eight eyes underwent complementary treatments of ischemic retina. Resolution of neovascularization was observed in 28 eyes (n = 28/35, 80%). Globe salvage was achieved in 51% (n = 18/35), including 25% of those with active tumor (n = 3/12). One eye became phthisic. Sixteen eyes were enucleated, nine for tumor relapse/progression. Five eyes had high-risk histopathologic risk factors and received adjuvant intravenous chemotherapy. All patients are alive with no extraocular extension nor metastases (mean follow-up 3.7 years, range 1.1-7.6).

CONCLUSION

Intravitreal anti-vascular endothelial growth factor contributed to a globe salvage rate of 51% by providing conditions to continue conservative treatment.

A 20-year audit of retinoblastoma treatment outcomes

Objectives

To evaluate the long-term treatment outcomes in intraocular retinoblastoma (RB) including the associated factors for eventual treatment with external beam radiotherapy (EBRT) and enucleation as well as to analyse the risk factors for metastasis and death in extraocular RB.

Methods

Retrospective analysis of 390 eyes from 256 (89.8%) intraocular RB and 29 (10.2%) extraocular RB cases diagnosed and treated between October 1998 and May 2018 at one of the largest tertiary care centers in Turkey.

Results

Of 351 intraocular RB eyes, 53.3% had group D/E disease at presentation. 75 (21.4%) of 351 eyes underwent primary enucleation. Of the remaining 276 eyes undergoing eye-conserving treatments, 201 (72.8%) were salvaged. Most of these eyes were treated using intravenous chemotherapy and/or focal treatments [transpupillary thermotherapy (TTT) and cryotherapy] initially. EBRT was eventually required in 48 (17.4%) eyes and secondary enucleation in 75 (27.2%) eyes. At mean follow-ups of 76.7 and 39.7 months for intraocular and extraocular RB cohorts, respectively, 180 (46.2%) eyes underwent primary/secondary enucleation and exenteration. Overall, 13 cases developed metastasis and 9 died. Two patients with trilateral RB also expired. Multivariable risk factors for enucleation were the presence of vitreous seeds (p < 0.001), absence of EBRT administration (p = 0.033), 5–9 TTT applications compared with no TTT (p = 0.031), and each 1 mm increase in tumour base diameter (p < 0.001). Univariate factors predictive of metastasis were the presence of extraocular RB detected by imaging methods (p < 0.001) and extrascleral/optic nerve cut end involvement at histopathological examination (p < 0.001).

Conclusions

In our series, 72.8% of the intraocular RB eyes undergoing eye-conserving treatments were saved. The globe salvage rate for all intraocular and extraocular RB eyes was 53.8% and the overall survival rate was 96.1%.

AAPM recommendations on medical physics practices for ocular plaque brachytherapy: Report of task group 221

The American Association of Physicists in Medicine (AAPM) formed Task Group 221 (TG-221) to discuss a generalized commissioning process, quality management considerations, and clinical physics practice standards for ocular plaque brachytherapy. The purpose of this report is also, in part, to aid the clinician to implement recommendations of the AAPM TG-129 report, which placed emphasis on dosimetric considerations for ocular brachytherapy applicators used in the Collaborative Ocular Melanoma Study (COMS). This report is intended to assist medical physicists in establishing a new ocular brachytherapy program and, for existing programs, in reviewing and updating clinical practices. The report scope includes photon- and beta-emitting sources and source:applicator combinations. Dosimetric studies for photon and beta sources are reviewed to summarize the salient issues and provide references for additional study. The components of an ocular plaque brachytherapy quality management program are discussed, including radiation safety considerations, source calibration methodology, applicator commissioning, imaging quality assurance tests for treatment planning, treatment planning strategies, and treatment planning system commissioning. Finally, specific guidelines for commissioning an ocular plaque brachytherapy program, clinical physics practice standards in ocular plaque brachytherapy, and other areas reflecting the need for specialized treatment planning systems, measurement phantoms, and detectors (among other topics) to support the clinical practice of ocular brachytherapy are presented. Expected future advances and developments for ocular brachytherapy are discussed.

Retinopathy in young retinoblastoma patients receiving a chemotherapy treatment: clinical trials and morphometric analysis

Background: This research is to evaluate patients with retinoblastoma, who receive chemotherapy, with enhanced depth imaging spectral-domain optical coherence tomography (EDI-OCT) to compare the signs of retinopathy.Materials and Methods: A prospective non-randomized trial included 125 eyes of 74 patients at the age of 24 ± 1.6 months with retinoblastoma. All patients underwent an ophthalmoscopic examination and EDI-OCT before therapeutic treatment. The test group consisted of 55 patients, who underwent a course of chemotherapy. Patients were divided into two groups depending on the type of chemotherapy. Group #1 patients received six cycles of systemic intravenous chemotherapy treatment, ophthalmoscopic examination, and EDI-OCT occurred after third cycle and sixth cycle. Group #2 underwent three cycles of IVC chemotherapy treatment, and then local chemotherapy - three cycles of super-selective intra-arterial chemotherapy for exophytic retinoblastoma and 9 procedures of intravitreal (IVT) for endophytic retinoblastoma. Eyes in the control group were affected by eccentric neoplasms but macula and the optic nerve were not damaged.Results: After six cycles of IVC chemotherapy treatment, Group #1 history expanded with atrophy-induced peripapillary nerve fiber layer thinning (33.9%). At three cycle of super-selective intra-arterial chemotherapy, OCT imaging in Group #2 revealed more related symptoms like retinal vascular distention in peritumoral area. After systemic and intravitreal chemotherapy, macular puckers and small hyperreflective dotted foci in the inner retina were tracked. In Group #3 affected by peripheral tumors, the topographic anatomy of the macula was normal prior to therapy.Conclusion: Profound morphometric disturbances that come with combined chemotherapy call for a more careful treatment with methods selected in terms of OCT findings and specific chemotherapy contraindications.

Conservative management of retinoblastoma: Challenging orthodoxy without compromising the state of metastatic grace. "Alive, with good vision and no comorbidity"

Retinoblastoma is lethal by metastasis if left untreated, so the primary goal of therapy is to preserve life, with ocular survival, visual preservation and quality of life as secondary aims. Historically, enucleation was the first successful therapeutic approach to decrease mortality, followed over 100 years ago by the first eye salvage attempts with radiotherapy. This led to the empiric delineation of a window for conservative management subject to a "state of metastatic grace" never to be violated. Over the last two decades, conservative management of retinoblastoma witnessed an impressive acceleration of improvements, culminating in two major paradigm shifts in therapeutic strategy. Firstly, the introduction of systemic chemotherapy and focal treatments in the late 1990s enabled radiotherapy to be progressively abandoned. Around 10 years later, the advent of chemotherapy in situ, with the capitalization of new routes of targeted drug delivery, namely intra-arterial, intravitreal and now intracameral injections, allowed significant increase in eye preservation rate, definitive eradication of radiotherapy and reduction of systemic chemotherapy. Here we intend to review the relevant knowledge susceptible to improve the conservative management of retinoblastoma in compliance with the "state of metastatic grace", with particular attention to (i) reviewing how new imaging modalities impact the frontiers of conservative management, (ii) dissecting retinoblastoma genesis, growth patterns, and intraocular routes of tumor propagation, (iii) assessing major therapeutic changes and trends, (iv) proposing a classification of relapsing retinoblastoma, (v) examining treatable/preventable disease-related or treatment-induced complications, and (vi) appraising new therapeutic targets and concepts, as well as liquid biopsy potentiality.

A convex windowless extrapolation chamber to measure surface dose rate from 106 Ru/106 Rh episcleral plaques

PURPOSE

A convex windowless extrapolation chamber was developed as a primary measurement device to determine surface dose rate from curved ¹⁰⁶ Ru/¹⁰⁶ Rh episcleral plaques.

METHODS

A convex extrapolation chamber without an entrance window was constructed for this work, and surface dose rate measurements were performed with two curved CCB-type ¹⁰⁶ Ru/¹⁰⁶ Rh plaques (S/N 2545 and 2596) manufactured by Eckert & Ziegler BEBIG. FARO ® Gage measurements were performed to verify the radius of curvature for the convex electrode and the concave plaque surface. Furthermore, the collecting electrode area was verified through capacitance measurements. Chamber correction factors for divergence and backscatter were generated using the EGSnrc cavity user code. For each source, surface dose rate was measured with the convex extrapolation chamber and compared with on-contact measurements made with curved un-laminated EBT3 film strips. A Monte Carlo correction was generated for radiochromic film measurements to account for volume averaging within the active layer and effects of phantom scatter. Additionally, extrapolation chamber results for each plaque were compared with scintillation detector measurements performed by the manufacturer. For the second source (S/N 2596), a comparison was also made with the Monte Carlo-corrected surface dose rate measured at the National Physical Laboratory (NPL) using cylindrical alanine pellets. Finally, source measurements were performed using conventional ionization chambers (Exradin A26, A1SL, and A20) within a custom fixture to investigate the transfer of extrapolation chamber surface dose rate to clinics.

RESULTS

For the first ¹⁰⁶ Ru/¹⁰⁶ Rh plaque (S/N 2545), average surface dose rate from the convex windowless extrapolation chamber was found to be 1.5% higher than the corresponding value from curved un-laminated EBT3 film measurements and 5.6% lower than the manufacturer value. For the second source (S/N 2596), the extrapolation chamber surface dose rate was 2.5% higher than the un-laminated EBT3 film result, 4.5% lower than the manufacturer value, and 3.9% higher compared to corrected alanine measurements made at NPL. Total uncertainty in the extrapolation chamber measurement was estimated to be approximately  ± 7.0% (k = 2). For the plaque measurements made using conventional ionization chambers with a custom fixture, surface dose rate from the transfer technique was found to agree within 3.8% with the expected convex extrapolation chamber result for S/N 2596.

CONCLUSIONS

A convex windowless extrapolation chamber was developed as a primary measurement device for ¹⁰⁶ Ru/¹⁰⁶ Rh plaques. Through comparison with the extrapolation chamber, the accuracy of surface dose rate measurements from current dosimetry techniques was assessed and agreement was seen within 5.6%. Finally, it was found that conventional ionization chambers could be calibrated with a reference ¹⁰⁶ Ru/¹⁰⁶ Rh plaque in order to transfer the extrapolation chamber result for surface dose rate to clinics.

The American Brachytherapy Society consensus guidelines for plaque brachytherapy of uveal melanoma and retinoblastoma

PURPOSE

To present the American Brachytherapy Society (ABS) guidelines for plaque brachytherapy of choroidal melanoma and retinoblastoma.

METHODS AND MATERIALS

An international multicenter Ophthalmic Oncology Task Force (OOTF) was assembled to include 47 radiation oncologists, medical physicists, and ophthalmic oncologists from 10 countries. The ABS-OOTF produced collaborative guidelines, based on their eye cancer-specific clinical experience and knowledge of the literature. This work was reviewed and approved by the ABS Board of Directors as well as within the journal's peer-reivew process.

RESULTS

The ABS-OOTF reached consensus that ophthalmic plaque radiation therapy is best performed in subspecialty brachytherapy centers. Quality assurance, methods of plaque construction, and dosimetry should be consistent with the 2012 joint guidelines of the American Association of Physicists in Medicine and ABS. Implantation of plaque sources should be performed by subspecialty-trained surgeons. Although there exist select restrictions related to tumor size and location, the ABS-OOTF agreed that most melanomas of the iris, ciliary body, and choroid could be treated with plaque brachytherapy. The ABS-OOTF reached consensus that tumors with gross orbital extension and blind painful eyes and those with no light perception vision are unsuitable for brachytherapy. In contrast, only select retinoblastomas are eligible for plaque brachytherapy. Prescription doses, dose rates, treatment durations, and clinical methods are described.

CONCLUSIONS

Plaque brachytherapy is an effective eye and vision-sparing method to treat patients with intraocular tumors. Practitioners are encouraged to use ABS-OOTF guidelines to enhance their practice.

Salvage/adjuvant brachytherapy after ophthalmic artery chemosurgery for intraocular retinoblastoma

PURPOSE

To evaluate the efficacy and toxicity of brachytherapy after ophthalmic artery chemosurgery (OAC) for retinoblastoma.

METHODS AND MATERIALS

This was a single-arm, retrospective study of 15 eyes in 15 patients treated with OAC followed by brachytherapy at (blinded institution) between May 1, 2006, and December 31, 2012, with a median 19 months' follow-up from plaque insertion. Outcome measurements included patient and ocular survival, visual function, and retinal toxicity measured by electroretinogram (ERG).

RESULTS

Brachytherapy was used as adjuvant treatment in 2 eyes and as salvage therapy in 13 eyes of which 12 had localized vitreous seeding. No patients developed metastasis or died of retinoblastoma. The Kaplan-Meier estimate of ocular survival was 79.4% (95% confidence interval 48.7%-92.8%) at 18 months. Three eyes were enucleated, and an additional 6 eyes developed out-of-target volume recurrences, which were controlled with additional treatments. Patients with an ocular complication had a mean interval between last OAC and plaque of 2.5 months (SD 2.3 months), which was statistically less (P=.045) than patients without ocular complication who had a mean interval between last OAC and plaque of 6.5 months (SD 4.4 months). ERG responses from pre- versus postplaque were unchanged or improved in more than half the eyes.

CONCLUSIONS

Brachytherapy following OAC is effective, even in the presence of vitreous seeding; the majority of eyes maintained stable or improved retinal function following treatment, as assessed by ERG.