Gamma knife stereotactic radiosurgery yields good long-term outcomes for low-volume uveal melanomas without intraocular complications

Magnetic Resonance Imaging in the Clinical Care for Uveal Melanoma Patients-A Systematic Review from an Ophthalmic Perspective

Conversely to most tumour types, magnetic resonance imaging (MRI) was rarely used for eye tumours. As recent technical advances have increased ocular MRI's diagnostic value, various clinical applications have been proposed. This systematic review provides an overview of the current status of MRI in the clinical care of uveal melanoma (UM) patients, the most common eye tumour in adults. In total, 158 articles were included. Two- and three-dimensional anatomical scans and functional scans, which assess the tumour micro-biology, can be obtained in routine clinical setting. The radiological characteristics of the most common intra-ocular masses have been described extensively, enabling MRI to contribute to diagnoses. Additionally, MRI's ability to non-invasively probe the tissue's biological properties enables early detection of therapy response and potentially differentiates between high- and low-risk UM. MRI-based tumour dimensions are generally in agreement with conventional ultrasound (median absolute difference 0.5 mm), but MRI is considered more accurate in a subgroup of anteriorly located tumours. Although multiple studies propose that MRI's 3D tumour visualisation can improve therapy planning, an evaluation of its clinical benefit is lacking. In conclusion, MRI is a complementary imaging modality for UM of which the clinical benefit has been shown by multiple studies.

Orbital indications

GKNS for uveal melanoma has become a recognized valued treatment which avoids enucleation of the eye. In the early days, the eccentric location of these tumors made treatment difficult, but Gamma Knife Perfexion has solved that problem. It is known that larger tumors and tumors with an anterior location have a worse prognosis. GKNS has also been of rather unexpected benefit in optic nerve gliomas that require treatment. Choroidal hemangiomas may benefit from treatment as can secondary glaucoma. It has also been found to be beneficial in the treatment of thyrotoxic ophthalmopathy.

Gamma knife radiosurgery for uveal melanomas and metastases: a systematic review and meta-analysis

BACKGROUND

Gamma knife radiosurgery is regarded as the gold-standard stereotactic radiosurgery modality for the treatment of intracranial tumours, and its use has been expanded for the treatment of intraocular malignancies. The aim of this study was to systematically evaluate the efficacy, outcomes, and complications of gamma knife radiosurgery for uveal melanomas and metastases.

METHODS

We did a systematic review and meta-analysis to aggregate the clinical outcomes of patients with uveal melanomas or intraocular metastases treated primarily with gamma knife radiosurgery. We searched MEDLINE and Embase for studies published between Sept 1, 1960, and Feb 1, 2020, reporting the use of gamma knife radiosurgery as primary treatment for uveal melanoma or uveal metastases. The search was restricted to clinical studies and relevant grey literature published in English. Studies reporting treatment of benign tumours, extraocular tumours, or other forms of stereotactic radiosurgery were excluded to reduce heterogeneity. No restrictions were placed on participant criteria. Local tumour control and tumour regression were extracted as the primary outcomes and analysed via a random-effects meta-analysis of proportions using the DerSimonian and Laird method with a Freeman-Tukey double arcsine transformation. This study is registered with PROSPERO, CRD42019148165.

FINDINGS

Our search returned 454 studies, of which 109 were assessed for full-text eligibility. 52 studies, reporting on 1010 patients with uveal melanoma and 34 intraocular metastases, were eligible for systematic review. 28 studies were included in the meta-analysis. 840 of 898 patients (0·96, 95% CI 0·94-0·97; I²=16%) from 19 studies had local control, and 378 of 478 patients (0·81, 0·70-0·90; I²=83%) from 16 studies experienced tumour regression.

INTERPRETATION

Gamma knife radiosurgery is an efficacious primary method of treating uveal melanomas and intraocular metastases, with reliable tumour control rates. Randomised controlled trials should further evaluate the safety and efficacy of gamma knife radiosurgery in this setting.

FUNDING

The Rhodes Trust and the Howard Brain Sciences Foundation.

A Case of Retinal Detachment with Unique Optical Coherence Tomography Findings after Gamma Knife® Radiosurgery Treatment for Choroidal Melanoma

Purpose

To report a case of retinal detachment with unique optical coherence tomography (OCT) findings after Gamma Knife® (GK; Elekta Instrument AB, Stockholm, Sweden) treatment for choroidal melanoma (CM).

Case Report

A 48-year-old woman underwent GK therapy for CM in her right eye from the macula to the temporal side. While the tumor subsequently shrank, the patient developed radiation retinopathy, which was treated with laser photocoagulation. The tumor lesions later subsided; however, her visual acuity (VA) decreased 8 years after the initial treatment. Although the tumor lesions in the right eye had become scarred, a bullous retinal detachment with fixed folds occurred in the superior-nasal quadrants. OCT examination revealed a preretinal membrane, vitreoretinal traction, and an inner retinal break; however, no outer retinal break was clearly detectable. MRI scans showed no increase in tumorous lesions, and ¹²³I-IMP SPECT imaging showed no photon accumulation. Thus, it was determined that there was no tumor activity. The corrected VA in her right eye was light perception, and it was determined that there was no indication for vitreous surgery.

Conclusion

In this case, an inner retinal break was formed by the vitreoretinal traction around the scarred tumor and radiation retinopathy, thus suggesting the possibility of the development of a rhegmatogenous retinal detachment presumably complicated with an outer retinal break.

Predictors of radio-induced visual impairment after radiosurgery for uveal melanoma

Aims

The aim of the present work is to assess the main predictors of the most clinically relevant radio-induced effects after Gamma Knife stereotactic radiosurgery (GKRS) for uveal melanoma (UM).

Materials and methods

Medical records and three-dimensional dosimetry data of critical structures of 66 patients were retrospectively reviewed. Cox’s proportional hazard model was used to identify clinical and dosimetric variables as independent risk factor for GKRS-related complications.

Results

The fraction of the posterior segment receiving more than 20Gy (V20), Bruch’s membrane rupture and tumour thickness were significant prognostic factors for neovascular glaucoma. A clear relationship with the dose received by 1% of the optic nerve (D1%) was found for radiation retinopathy and papillopathy. Multivariables models resulted for visual acuity (VA) reduction >20% of the basal value and for complete VA loss, both including largest tumour diameter and D1% to the optic nerve. The predictive model for complete VA loss includes also Bruch’s membrane rupture. An alternative model for complete visual acuity loss, including the optic nerve-prescription isodose minimum distance, was also suggested.

Conclusions

We found clinical and dosimetric variables to clearly predict the risk of the main side effects after GKRS for UM. These results may provide dose constraints to critical structures, potentially able to reduce side effects. Constraining D1% to the optic nerve below 12-13Gy may result in a dramatic reduction of blindness risk, while reducing V20 of the posterior segment of the bulb could limit the neovascular glaucoma onset.

The evolving role of radiation therapy in the management of malignant melanoma

The incidence of melanoma is rising in the United States, leading to an estimated 68,720 new diagnoses and 8,650 deaths annually. The natural history involves metastases to lymph nodes, lung, liver, brain, and often to other sites. Primary treatment for melanoma is surgical excision of the primary tumor and affected lymph nodes. The role of adjuvant or definitive radiation therapy in the treatment of melanoma remains controversial, because melanoma has traditionally been viewed as a prototypical radioresistant cancer. However, recent studies suggest that under certain clinical circumstances, there may be a significant role for radiation therapy in melanoma treatment. Stereotactic radiosurgery for brain metastases has shown effective local control. High dose per fraction radiation therapy has been associated with a lower rate of locoregional recurrence of sinonasal melanoma. Plaque brachytherapy has evolved into a promising alternative to enucleation at the expense of moderate reduction in visual acuity. Adjuvant radiation therapy following lymphadenectomy in node-positive melanoma prevents local and regional recurrence. The newer clinical data along with emerging radiobiological data indicate that radiotherapy is likely to play a greater role in melanoma management and should be considered as a treatment option.