Efficacy and complications of ruthenium-106 brachytherapy for uveal melanoma: a systematic review and meta-analysis

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.

Yttrium-90 Episcleral Plaque Brachytherapy for Choroidal Melanoma

Purpose: To describe the first use of high-dose-rate yttrium-90 disc brachytherapy for choroidal melanoma. Methods: A 72-year-old patient had a cT1-category choroidal melanoma characterized by the presence of orange pigment, increasing subretinal fluid (SRF), and enlarging tumor thickness. It was treated with single-session, light-guided, light-defined yttrium-90-disc brachytherapy. Results: A specialized handheld applicator provided with 4 encircling lights was used to guide plaque placement and localize treatment. Unlike low-dose-rate plaques, high-dose-rate yttrium-90 required only 3 minutes 39 seconds. In this case, treatment did not require episcleral sutures, muscle relocation, outpatient dwell time, or a second surgery. High-dose-rate treatment improved radiation safety by eliminating perioperative exposure to health care personnel, the community, and the family. At the 13-month follow-up, the SRF and tumor thickness were diminished. There was no secondary cataract, radiation retinopathy, maculopathy, or optic neuropathy, and the visual acuity was 20/20. Conclusions: Yttrium-90 brachytherapy allowed for single-surgery, minimally invasive, outpatient irradiation of a choroidal melanoma.

Radiation retinopathy following episcleral brachytherapy for intraocular tumors: Current treatment options

Radiation retinopathy (RR) and radiation maculopathy (RM) can occur as a result of uveal melanoma radiation treatment and after irradiation of other head and neck extraocular tumors, even with precise targeting techniques, such as stereotactic or proton beam radiotherapy. This review provides an overview of the current understanding of potential radiation damage to ocular tissues, and how recent developments in ophthalmic multimodal imaging techniques and treatment modalities have improved managing options. Several treatment strategies have been employed so far for the management of RR, including laser photocoagulation, intravitreal injections of anti-vascular endothelial growth factor (VEGF) agents or glucocorticosteroids and surgery. The use of intravitreal anti-VEGFs or dexamethasone implants have significantly altered the final visual outcome for uveal melanoma patients. As a prophylaxis, a few different strategies were proposed, but still there is a lack of large randomized clinical trials supporting these approaches and clear clinical guidelines for daily practice. Early detection and proper treatment are crucial in preventing or reducing vision loss, and improving patients' quality of life. Close monitoring and timely intervention are essential for successful management.

Subconjunctival Ocular Argyrosis following Treatment with Ruthenium 106 Brachytherapy for Choroidal Melanoma

Introduction

Ruthenium-106 (Ru-106) brachytherapy is one of the commonest eye-sparing treatments for choroidal melanoma. These patients require long-term surveillance of the treated tumour remnant to ensure there is no local recurrence. New or progressive pigmented lesions in treated eyes are often regarded as suspicious - especially if there are concerns of extra-scleral extension.

Case Presentations

We present two cases of posterior choroidal melanoma treated five and 10 years previously with Ru-106. Both cases developed subconjunctival dark/black lesions on the anterior surface of the eye in the quadrant of the conjunctival peritomy during Ru-106 treatment. Both had similar findings on histopathology: black, non-organic, particulate foreign material of varying confluence deposited on elastin and collagen fibres. Energy dispersive X-ray microanalysis confirmed the material contained silver.

Discussion

The Ru-106 applicator consists of a radioactive core of Ru-106 encapsulated within pure silver as a radiation shield. During surgical insertion, stainless steel suture needles and forceps can occasionally scratch the applicator's silver eyelets and scatter microscopic particles of elemental silver into the operative field. These particles were likely deposited within the subconjunctival tissues of these patients during brachytherapy administration, leading to localised ocular argyrosis. Iatrogenic ocular argyrosis should be considered in the differential diagnosis of new pigmented lesions in patients treated with Ru-106 brachytherapy. This study is the first to unequivocally identify the cause of some post-brachytherapy ocular surface pigmentation as caused by silver.

Deterioration of Visual Acuity after Brachytherapy and Proton Therapy of Uveal Melanoma, and Methods of Counteracting This Complication Based on Recent Publications

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. The eyeball is the most common extracutaneous location of melanoma. UM is a huge threat to a patient's life. It metastasizes distantly via blood vessels, but it can also spread locally and infiltrate extraocular structures. The treatment uses surgical methods, which include, among others, enucleation and conservative methods, such as brachytherapy (BT), proton therapy (PT), stereotactic radiotherapy (SRT), stereotactic radiosurgery (SRS), transpupillary thermotherapy (TTT) and photodynamic therapy. The key advantage of radiotherapy, which is currently used in most patients, is the preservation of the eyeball with the risk of metastasis and mortality comparable to that of enucleation. Unfortunately, radiotherapy very often leads to a significant deterioration in visual acuity (VA) as a result of radiation complications. This article is a review of the latest research on ruthenium-106 (Ru-106) brachytherapy, iodine-125 (I-125) brachytherapy and proton therapy of uveal melanoma that took into account the deterioration of eye function after therapy, and also the latest studies presenting the new concepts of modifications to the applied treatments in order to reduce radiation complications and maintain better visual acuity in treated patients.

Current management of uveal melanoma: A review

Uveal melanoma is the most frequent primary intraocular cancer in adulthood and is mostly localised to the choroid. It can be treated using radiation therapy, laser therapy, local resection and enucleation, with the best results achieved by combining these procedures. However, up to half of patients develop metastatic disease. There are no efficacious treatment methods for patients in advanced stage or with metastasis. In recent years, several novel treatment modalities aimed at improving tumour control and reducing adverse events have emerged. This review summarises current clinical treatment methods and new therapeutic perspectives for uveal melanoma.

Long-term visual outcomes after ruthenium plaque brachytherapy for posterior choroidal melanoma

BACKGROUND

To assess the long-term visual outcomes in patients with posteriorly located choroidal melanoma treated with ruthenium plaque brachytherapy between January 2013 and December 2015.

METHODS

A retrospective review was conducted on consecutive patients treated with ruthenium plaque brachytherapy for post-equatorial choroidal melanoma with available Snellen visual acuity before and after treatment, and the development and treatment of radiation complications.

RESULTS

There were 219 patients with posterior choroidal melanoma treated with ruthenium plaque brachytherapy. Median follow up was 56.5 months, range 12-81 months. Final visual acuity was ≥6/12 in 97 (44.3%) patients, 6/12 to 6/60 in 57 (26.0%), <6/60 in 55 (25.1%) and 10 (4.6%) eyes were enucleated. Radiation maculopathy was the most common radiation complication encountered, occurring in 53 (24.2%) patients. Of these, final visual acuity was 6/12 in 10 patients (18.9%), 6/12 to 6/60 in 26 (49.1%), <6/60 in 16 (30.2%) and 1 eye (1.9%) was enucleated. Twenty-five (47%) with radiation maculopathy were treated with intravitreal anti-angiogenic therapy, 27 (51%) were monitored and one (2%) was treated with scatter photocoagulation. Eyes treated with intravitreal anti-angiogenic therapy had better final vision than those observed or treated with retinal laser (chi-square, p = 0.04). On multivariate analysis, close proximity to the optic nerve and fovea, and large or notched plaque type was associated with final vision worse than 6/12.

CONCLUSION

Most patients treated with ruthenium plaque brachytherapy for posterior choroidal melanoma retain 6/60 vision, with almost half retaining 6/12 vision at long term follow up.

Anatomical and Functional Outcomes after Endoresection and Adjuvant Ruthenium Brachytherapy for Uveal Melanoma: A Single-Center Experience

PURPOSE

To evaluate the anatomical and functional outcomes of endoresection and adjuvant ruthenium (Ru)-106 brachytherapy for uveal melanoma (UM).

METHODS

Retrospective case series of 15 UM patients (15 eyes) treated at our center (Careggi University Hospital, Florence).

RESULTS

Six patients (40%) were male and nine were female (60%). The mean age of patients at the time of treatment was 61.6 years (±19.41). The mean BCVA at baseline was 20/50. In all cases UM originated from the choroid. The mean tumor thickness at baseline was 7.14 mm (±2.05), and the mean largest basal diameter was 11.2 mm (±1.92). A concurrent retinal detachment was diagnosed in 11 patients (73.3%). Two patients (13.3%) showed vitreous seeding at baseline. Eleven patients (73.3%) were treated with primary endoresection, while four patients (26.7%) were treated with a "salvage endoresection" after primary treatment failure (previous radiation treatment). The mean follow-up time was 28.9 months (±10.6). Thirteen out of fifteen patients were alive and showed no evidence of local recurrence or distance metastasis at the last follow-up visit. The treatment achieved local control of the disease in 14 out of 15 cases (93.3%). In one case, the patient underwent enucleation for disease recurrence. The overall survival rate at the end of the follow-up was 93.3%. The mean BCVA at last follow-up visit was 20/40. Treatment was well tolerated, without significant complications.

CONCLUSIONS

Endoresection and adjuvant Ru-106 brachytherapy is a valuable conservative option for selected UM patients and can be used both as a primary treatment and as a salvage therapy. It can control melanoma and avoid enucleation, reduce radiation-related complications, and provide tumor tissue for chromosomal analysis and prognostic testing.

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.

Ocular Brachytherapy (Interventional Radiotherapy): Preserving the Vision

Uveal melanoma represents the most common intraocular neoplasia among adults. Brachytherapy (interventional radiotherapy; IRT) has a great advantage, when compared with enucleation, both in terms of organ and function sparing. The Collaborative Ocular Melanoma Study introduced into clinical practice a standardised procedure that allowed the equivalence of IRT with enucleation in terms of overall survival to be demonstrated. IRT is carried out by placing a plaque in direct contact with the sclera under the uveal melanoma. Several radioactive sources may be used, including 106-ruthenium, 125-iodine, 103-palladium and 90-strontium. It is a multidisciplinary procedure requiring the collaboration of interventional radiation oncologists and ophthalmologists in the operating theatre and medical physicists for an accurate treatment time calculation. It also relies on ultrasound imaging to identify the lesion and verifiy the correct plaque placement. An emerging tool of paramount importance could be the use of artificial intelligence and predictive models to identify those patients at higher risk of developing late side-effects and therefore who may deserve preventive and supportive therapies.

Robotic CyberKnife Radiosurgery for the Treatment of Choroidal and Ciliary Body Melanoma

PURPOSE

To present the results of robotic-assisted radiosurgery in choroidal and ciliary body melanomas treated at the Department of Ophthalmology of Ludwig-Maximilians-University and the European CyberKnife Center in Munich, Germany.

DESIGN

Interventional case series METHODS: This retrospective study included 594 consecutive patients referred to our clinic for the treatment of choroidal and ciliary body melanomas with robotic radiosurgery (CyberKnife) from 2005 to 2019. Eye retention, local control and disease-specific survival rates were calculated as Kaplan-Meier and actuarial estimates. The impact of prescription dose, tumor size, and ciliary body involvement was assessed by likelihood ratio tests and Cox regression.

RESULTS

Among all patients who were staged according to the TNM classification system (8th edition), 22.7% were I, 57.9% were II, 18.9% were III, and 0.5% were IV. Median apical tumor height and base diameter were 5.8 and 11.4 mm. The mean follow-up was 41.7 months. Local control after 3 and 5 years was 92.0% (95% CI = 88.2%-94.7%) and 84.3% (95% CI = 77.9%-89.0%), respectively, for 21 to 22 Gy and 86.9% (95% CI = 79.7%-91.7%) and 77.7% (95% CI = 68.5%-84.6%), respectively, when treated with 20 Gy or less. Eye retention was achieved in 89.9% and 81.0% after 3 and 5 years with 21 to 22 Gy and 85.9% and 80.0% for 20 Gy or less. Disease-specific survival rates were 93.1% (95% CI = 90.2%-95.2%) after 3 years, 89.8% (95% CI = 86.0%-92.6%) after 5 years, and 87.8% (95% CI = 82.8%-91.4%) after 7 years.

CONCLUSIONS

This is the largest series of patients treated for choroidal and ciliary body melanomas with CyberKnife. Our results reflect an improvement in the outcome of CyberKnife therapy for patients with choroidal and ciliary body melanoma treated with single-session radiosurgery in the last decade.

Ocular Complications of Radiotherapy in Uveal Melanoma

Uveal melanoma is the most common primary malignant intraocular tumor in adults. Radiation therapy has replaced enucleation and is now the preferred treatment in most cases. Nonetheless, around 70% of patients develop radiation-related complications, some of which are vision-threatening. The objective of this review is to present the most important complications associated with radiotherapy in the treatment of uveal melanoma and their pathogenesis, incidence, risk factors, and available preventive and therapeutic measures. The most common complications are cataracts, with a reported incidence ranging from 4% to 69%, and radiation retinopathy, reported in 5-68% of cases. Radiation-related complications are responsible for approximately half of secondary enucleations, the leading cause being neovascular glaucoma. A poor visual outcome is mainly associated with the presence of radiation retinopathy and radiation optic neuropathy. Therapeutic options are available for the majority of complications with the notable exception of optic neuropathy. However, many studies report a final visual acuity of less than 20/200 in more than 60% of treated eyes. Reducing complication rates can be achieved by lowering the dose of radiation, with the use of eccentric, customized plaques and careful planning of the irradiation delivery in order to protect structures vital to vision and by associating radiation therapy with other methods with the aim of reducing tumor volume.

Clinical Outcomes after Surgical Resection Combined with Brachytherapy for Uveal Melanomas

Currently, brachytherapy is the most commonly used therapeutic approach for uveal melanomas. Surgical resection by means of endoresection or exoresection is an alternative approach. The present report recounts our experience over 15 years in the treatment of uveal melanoma using a combined approach of resection surgery with brachytherapy. This is a single-center observational retrospective cohort study in which we describe clinical outcomes, complications and survival in 35 cases of melanoma of the iris or the ciliary body after a combination of surgery and brachytherapy or brachytherapy alone. Local treatment of the tumor was successful in all cases with surgery and brachytherapy. The most frequent complications were scleromalacia, bullous keratopathy, retinal toxicity, cataracts, hypotonia, and photophobia. There were three cases of recurrence, all of which were found in the group of patients who had received brachytherapy alone, and in one case we had to perform a secondary enucleation due to tumor growth after brachytherapy. At present, only one patient has died during follow-up due to liver metastases six years after the start of treatment. In carefully selected patients, this approach can be effective and safe, as long as a close follow-up is carried out after surgery.

Radiological and clinical findings in uveal melanoma treated by plaque interventional radiotherapy (brachytherapy): Visual atlas and literature review on response assessment

Uveal melanoma (UM) is the most common intra-ocular tumor in Caucasian adults and may derive from melanocytes. Historically, the first therapeutic approach to treat UM has been surgical removal of the eye, with obvious consequences in terms of function, cosmesis, and psychological impact on patients. Collaborative Ocular Melanoma Study (COMS) introduced the first uniform approach to perform interventional radiotherapy (IRT - brachytherapy) procedure in a standardized way that allowed to demonstrate equivalence of IRT with enucleation in terms of overall survival. Since this milestone, several international guidelines have been issued with regard to several technical aspects of this procedure, which has become the mainstream therapy worldwide. However, nowadays, there is still a lack of consensus about the criteria to definitively assess UM response after IRT. We present a collection of paradigmatic cases treated in our institution, and then discuss in detail the latest available evidence on the topic.

Brachytherapy in organ-preserving treatment of choroidal melanoma: complications and the possibility of their prediction

This review analyzed the domestic and foreign literature on brachytherapy of choroidal melanoma using ruthenium ophthalmic applicators. The review highlights the historical aspects of radiation treatment, from the first experience of using ionizing radiation in the treatment of malignant neoplasms to modern methods of brachytherapy; presents the radiobiological foundations of radiation therapy; considers the issues of radiation pathomorphosis, reflecting the nature of pathological changes in the choroidal melanoma tissue during brachytherapy; shows the dependence of the effect of exposure ionizing radiation from the phase of the cycle of cell division; and also describes the presence of changes characteristic of the response to ionizing radiation in unirradiated tissues. The analysis of various post-radiation complications, both early and late, was carried out in some detail, with emphasis on the possibility of predicting and preventing them in real clinical practice. A comparison is made in terms of the frequency of development of various post-radiation complications in the works of domestic and foreign authors, as well as a comparison with the effect of ionizing radiation from other radioactive isotopes. Recommendations of experts are given regarding the correct calculation of the dose to the sclera and medication support, based on many years of experience in the use of ruthenium ophthalmic applicators for brachytherapy of choroidal melanoma. The risks of developing such late complications as radiation maculopathy and radiation neuropathy have been demonstrated, especially in pre-equatorial tumor localization. The possibilities of modern methods of instrumental diagnostics for studying the processes occurring in the area of the tumor, as well as changes in the surrounding tissues, are shown, which determines the feasibility and importance of further study of this issue.

Radiobiological evaluation of organs at risk for electronic high-dose-rate brachytherapy in uveal melanoma: a radiobiological modeling study

Purpose

The objective of this study was to examine feasibility of single- or hypo-fraction of high-dose-rate (HDR) electronic brachytherapy (eBT) in uveal melanoma treatment.

Material and methods

Biologically effective doses (BED) of organs at risk (OARs) were compared to those of iodine-125-based eye plaque low-dose-rate brachytherapy (¹²⁵I LDR-BT) with vitreous replacement (VR). Single- or hypo-fractionated equivalent physical doses (SFEDs or HFEDs) for tumor were calculated from tumor BED of ¹²⁵I LDR-BT using linear-quadratic (LQ) and universal survival curve (USC) models. BED OARs doses to retina opposite the implant, macula, optic disc, and lens were calculated and compared among SFED, HFED, and ¹²⁵I LDR-BT. Electronic BT of 50 kVp was considered assuming dose fall-off as clinically equivalent to ¹²⁵I LDR-BT. All OARs BEDs were analyzed with and without silicone oil VR.

Results

For a single-fraction incorporating VR, the median/interquartile range of LQ (USC)-based BED doses of the retina opposite the implant, macula, optic disc, and lens were 16%/1.2% (33%/4%), 35%/19.5% (64%/17.7%), 37%/19% (75%/17.8%), and 27%/7.9% (68%/23.2%) of those for ¹²⁵I LDR-BT, respectively. SFED tumor values were 29.8/0.2 Gy and 51.7/0.5 Gy when using LQ and USC models, respectively, which could be delivered within 1 hour. SFED can be delivered within 1 hour using a high-dose-rate eBT. Even four-fraction delivery of HFED without VR resulted in higher OARs doses in the macula, optic disc, and lens (135 ~ 159%) than when using ¹²⁵I LDR-BT technique. A maximum p-value of 0.005 was observed for these distributions.

Conclusions

The simulation of single-fraction eBT, including vitreous replacement, resulted in significantly reduced OARs doses (16 ~ 75%) of that achieved with ¹²⁵I LDR-BT.