Intravitreal bevacizumab combined with plaque brachytherapy reduces melanoma tumor volume and enhances resolution of exudative detachment

Radiotherapy in Uveal Melanoma: A Review of Ocular Complications

Uveal melanoma represents the most prevalent form of primary malignant intraocular tumor in adults. Historically, enucleation was considered the gold-standard approach in the treatment of uveal melanoma. Currently, radiotherapy is the most commonly used therapy, aiming at a better quality of life. However, radiotherapy can result in several ocular complications, some of which may be vision-threatening. Radiation-induced dry eye, scleral necrosis, cataract, rubeosis iridis, neovascular glaucoma, radiation retinopathy, maculopathy, and optic neuropathy are the most common complications. This article aims to summarize the current literature regarding the ocular complications after radiotherapy, as well as their clinical features, risk factors, and management strategies. A thorough understanding of these issues is crucial for ophthalmologists and oncologists to provide optimal patient care, improve visual outcomes, and minimize long-term complications.

Non-Cancer Effects following Ionizing Irradiation Involving the Eye and Orbit

Simple Summary

The irradiation of tumors involving the eye or orbit represents a complex therapeutic challenge due to the proximity between the tumor and organs that are susceptible to radiation. The challenges include tumor control, as it is often a surrogate for survival; organ (usually the eyeball) preservation; and the minimization of damage of sensitive tissues surrounding the tumor in order to preserve vision. Anticipation of the spectrum and severity of radiation-induced complications is crucial to the decision of which technique to use for a given tumor. The aim of the present review is to report the non-cancer effects that may occur following ionizing irradiation involving the eye and orbit and their specific patterns of toxicity for a given radiotherapy modality. The pros and cons of conventional and advanced forms of radiation techniques and their clinical implementation are provided with a clinical perspective.

Abstract

The eye is an exemplarily challenging organ to treat when considering ocular tumors. It is at the crossroads of several major aims in oncology: tumor control, organ preservation, and functional outcomes including vision and quality of life. The proximity between the tumor and organs that are susceptible to radiation damage explain these challenges. Given a high enough dose of radiation, virtually any cancer will be destroyed with radiotherapy. Yet, the doses inevitably absorbed by normal tissues may lead to complications, the likelihood of which increases with the radiation dose and volume of normal tissues irradiated. Precision radiotherapy allows personalized decision-making algorithms based on patient and tumor characteristics by exploiting the full knowledge of the physics, radiobiology, and the modifications made to the radiotherapy equipment to adapt to the various ocular tumors. Anticipation of the spectrum and severity of radiation-induced complications is crucial to the decision of which technique to use for a given tumor. Radiation can damage the lacrimal gland, eyelashes/eyelids, cornea, lens, macula/retina, optic nerves and chiasma, each having specific dose–response characteristics. The present review is a report of non-cancer effects that may occur following ionizing irradiation involving the eye and orbit and their specific patterns of toxicity for a given radiotherapy modality.

Experiences of two different modalities in the management of choroidal melanoma in the Asian Indian population

BACKGROUND

Choroidal malignant melanoma is a rare intraocular cancer in Asian Indian population. There is a paucity of data from our population comparing iodine 125 (I-125) brachytherapy and enucleation.

AIM

This study aims to compare two groups of choroidal melanoma patients treated with either I-125 brachytherapy or enucleation in the Asian Indian population.

OBJECTIVES

To evaluate the long-term morbidity and mortality rates in choroidal melanoma patients treated with either I-125 brachytherapy or enucleation.

METHODS

It is a retrospective study involving forty four eyes, diagnosed with choroidal melanoma from May 2008 to February 2015. All were evaluated preoperatively for metastasis. Twenty-two underwent globe salvaging I-125 brachytherapy surgery whereas remaining 22 underwent globe destructive primary enucleation procedure.

RESULTS

At a mean follow-up 39 months, 2 of 22 cases (9%) died in the brachytherapy group. One was secondary to metastasis in the liver while the other case died of a natural cause. In the enucleation group also, there were two deaths (9%) secondary to metastasis. The metastasis free survival was 95% in the brachytherapy group and 91% in the enucleation group, which was not statistically significant (P = 0.3577). Kaplan-Meier survival at 3 years and 5 years was 95% and 89% for brachytherapy group and 94% and 89% for enucleation group.

CONCLUSION

This study found no difference in the long-term survival of choroidal melanoma patients treated with either brachytherapy or enucleation in the Asian Indian eyes.

Quantifying Subclinical and Longitudinal Microvascular Changes Following Episcleral Plaque Brachytherapy Using Spectral Domain-Optical Coherence Tomography Angiography

PURPOSE

To assess longitudinal microvascular changes in eyes treated with I-125 episcleral plaque brachytherapy (EPB).

METHODS

High resolution OCT angiograms of the central 3×3mm macula were obtained from I-125 episcleral plaque brachytherapy treated and untreated fellow eyes of 61 patients. Capillary density (vessel skeleton density, VSD) and caliber (vessel diameter index, VDI) were quantified using previously validated semi-automated algorithms. Nonperfusion was also quantified as flow impairment regions (FIR). Exams from treated and fellow eyes obtained pre-treatment and at 6-month, 1-year, and 2-year intervals were compared using generalized estimating equation linear models. Dosimetry maps were used to evaluate spatial correlation between radiation dose and microvascular metrics.

RESULTS

At 6 months, treated eyes had significantly lower VSD (0.145 ± 0.003 vs 0.155 ± 0.002; p = 0.009) and higher FIR (2.01 ± 0.199 vs 1.46 ± 0.104; p = 0.010) compared to fellow eyes. There was a significant decrease in VSD and a corresponding increase in FIR even for treated eyes without clinically identifiable retinopathy at 6 months. VDI was significantly higher in treated eyes than in fellow eyes at 2 years (2.92 ± 0.025 vs 2.84 ± 0.018; p < 0.001). When our cohort was categorized into low dose radiation (<15Gy) and high dose radiation (>45Gy) to the fovea, there were significant differences in VSD and FIR between groups.

CONCLUSIONS

OCTA can be used to quantify and monitor EPB induced retinopathy, and can detect vascular abnormalities even in the absence of clinically observable retinopathy. OCTA may therefore be useful in investigating treatment interventions that aim to delay EPB-induced radiation retinopathy.

Complications and adverse events of plaque brachytherapy for ocular melanoma

Plaque brachytherapy is a well-accepted modality to manage selected cases of ocular melanoma. Although this modality provides validated oncologic and quality of life benefits, severe complications and adverse events can occur. This article reviews complications and adverse events of plaque brachytherapy, including scleral necrosis, strabismus, cataract, glaucoma, and retinopathies as well as management of these conditions. For practicing oncologists and ophthalmologists, these complications are important to understand, identify, and treat. Additionally, an understanding of common complications of brachytherapy should influence the decision of pursuing it as a treatment option.

Low-dose brachytherapy strategies to treat uveal melanoma: is less more?

The Collaborative Ocular Melanoma Study (COMS) has established equivalency of globe salvaging brachytherapy compared with enucleation in terms of survival for medium-sized choroidal melanoma. The radiation dose protocol followed by the COMS was 85 Gray to a prescription point of the tumor apex or 5 mm inner sclera; whichever was greater. While the COMS realized appropriate local and distant tumor control rates, ocular morbidity due to radiation complications remains a significant clinical challenge. Recent studies challenge the COMS radiation dose paradigm by demonstrating similar tumor control by utilizing lower radiation doses that are associated with reduced radiation toxicity. Improved operative techniques including intraoperative ultrasound can aid to obtain adequate radiation delivery to the tumor by ensuring optimal plaque position. Adjuvant transpupillary thermotherapy, intravitreal anti-VEGF and posterior sub-Tenon steroids may further enhance outcome by providing additional tumor control and/or facilitating visual recovery.