Chapter 143 Overview of Management of Posterior Uveal Melanoma
Introduction
Even though there continue to be numerous publications on management of uveal melanoma, the subject remains controversial.1–74 Depending on the clinical circumstances, observation, transpupillary thermotherapy, plaque radiotherapy, charged particle irradiation, local resection, enucleation, orbital exenteration, chemotherapy, and immunotherapy are still being employed.1 There has been a trend away from laser photocoagulation alone with continued interest in transpupillary thermotherapy alone, or as supplemental treatment to radiotherapy for medium-sized and some large melanomas. The recently recognized clinical risk factors for metastasis for small choroidal melanomas are being used to select treatment and counsel patients.2 Consequently, there is a trend away from observation of some small melanocytic lesions and a trend toward earlier treatment of lesions that possess those risk factors.3 Updated results for treating uveal melanoma with plaque brachytherapy and charged particles have been published. This introductory chapter provides an overview of the methods of managing patients with ciliary body and choroidal melanoma. In the subsequent chapters, several authorities address the details of various therapeutic modalities.
General considerations
Historically, enucleation was once considered to be the only appropriate management for a patient with a posterior uveal melanoma. Several years ago, however, some authorities challenged the effectiveness of enucleation for preventing metastatic disease and even proposed that enucleation may somehow promote or accelerate metastasis.4,5 The validity of these arguments was challenged by others, who believed that early enucleation offered the patient the best chance of cure.6,7 This controversy over enucleation was responsible for initiating a trend away from enucleation and the increasing use of more conservative therapeutic methods.
Depending upon several clinical factors, the most common methods of management today include observation, transpupillary thermotherapy (TTT), radiotherapy, local resection, enucleation, orbit exenteration, and various combinations of these methods. There is currently an increasing variety of methods to treat or prevent metastatic disease that are beyond the scope of this short chapter. The most frequently employed treatment methods today are radiotherapy and enucleation. The Collaborative Ocular Melanoma Study (COMS) was organized to address several issues related to uveal melanoma and important information has been obtained from that study.8–12 Nevertheless, each case must be individualized and one should recommend the treatment that is believed to provide the best systemic prognosis, while preserving as much vision as possible. If possible, the patient should be referred to an ocular oncologist or other ophthalmologist who has experience in managing patients with posterior uveal melanoma.
Periodic observation
Some small melanocytic tumors are best managed by periodic fundus photography and ultrasonography to document growth of the lesion before recommending definitive treatment.13 Identified risk factors for metastasis include greater tumor thickness, tumor proximity to the optic nerve, presence of visual symptoms from the melanoma, and prior documented growth.2,14 Since documented growth may be associated with a worse systemic prognosis, there is a trend to treat patients who have the other risk factors, without necessarily waiting for documentation of growth.3 Tumors that show highly suspicious features or unequivocal evidence of growth should generally have some form of active therapy, depending upon the factors mentioned previously.
Photocoagulation
Photocoagulation was once a commonly used method to treat small choroidal melanomas.15–17 It was originally done with xenon photocoagulation but argon laser subsequently became more commonly employed. Studies showed that xenon photocoagulation achieved better tumor control but argon laser was associated with fewer complications.16 Recently, TTT has largely replaced argon laser for treating selected small melanomas that are less than 3 mm in thickness and located more than 3 mm from the foveola.18
Transpupillary thermotherapy
TTT is a recently popularized method of treating selected small and medium-sized choroidal melanomas.18–20 It delivers heat to the tumor in the infrared range using a modified diode laser delivery system. It does not appear to produce as much damage to the sensory retina as does laser photocoagulation. Recent observations have clarified the limitations and complications of TTT.20 It is used frequently as a supplement to plaque radiotherapy.21
Radiotherapy
Radiotherapy is still the most widely employed treatment for posterior uveal melanoma. The most commonly used form of radiotherapy has been the application of a radioactive plaque.8–10,22,23 Several years ago, most melanomas were treated with a Cobalt 60 plaque.24 More recently, Iodine-125 and Ruthenium-106 plaques have largely replaced Cobalt-60 at most institutions.25–27 It was originally believed to be useful for small and medium-sized melanomas that were outside the retinal vascular arcade and posterior to the ora serrata. Although the COMS failed to address tumors in other locations, some studies have presented the rationale for using plaque radiotherapy for macular melanoma,28 ciliary body melanoma,29 large melanoma,23 and melanoma with extrascleral extension.22
Another method of radiotherapy is charged particle irradiation.30–32 Although this technique was originally believed to provide a collimated beam that would limit the radiotherapy to the precise area of the tumor, this theory has not been substantiated by clinical experience. Similar complications occurred with radioactive plaques. It appears that survival, visual results, and complications are very similar with plaque and charged particle treatment.
On the basis of available information, it appears that patients treated with radiotherapy have a survival rate similar to those treated by enucleation.8 Furthermore, there is probably no significant difference between plaque radiotherapy and charged particle radiotherapy with regard to short-term and long-term complications. Studies have shown that between 5% and 10% of patients treated with radiotherapy ultimately require enucleation because of tumor recurrence or radiation complications.33,34
Local resection
Local resection of melanomas involving the ciliary body and choroid continues to be popular in some centers.15,35 We initially began using the technique of penetrating sclero-uveo-retinectomy (full-thickness eye wall resection) as advocated by Meyer-Schwickerath36 and later popularized by Peyman and associates.37 Although there are a number of potential serious complications, the eye can tolerate fairly extensive resections. More recently, we have employed a partial lamellar sclerouvectomy, a modification of the technique popularized by Foulds and Damato, in which the tumor is removed with the aim of leaving the retina and vitreous intact.15 Our surgical technique and results for this procedure are reported.35,38,39
Some authorities have reported experience with endoresection of choroidal melanoma, by removing tumor with a vitrectomy approach, and a few authorities are now using endoresection to remove choroidal melanoma after plaque radiotherapy or charged particle irradiation. Long-term follow-up will be necessary to determine the validity of endoresection techniques.40,41
Enucleation
As mentioned earlier, the traditional method of treating uveal melanomas by enucleation was challenged several years ago.4,5 Others continued to believe that enucleation was an appropriate method of management.6,7 Enucleation is generally indicated for advanced melanomas that occupy most of the intraocular structures and for those that have produced severe secondary glaucoma. Another relative indication for enucleation is a melanoma that has invaded the optic nerve. Enucleation with a long section of the optic nerve seems more reasonable in such cases. However, many juxtapapillary melanomas, that have not actually invaded the nerve, can often be managed by custom-designed notched radioactive plaques.42–45 The so-called “no touch enucleation” was introduced a number of years ago to minimize the amount of surgical trauma and theoretically to lessen the chance of tumor dissemination at the time of surgery.46 An essential aspect of this technique was to freeze the venous drainage from the tumor prior to cutting the optic nerve. The “no touch” technique has recently fallen into disuse at most centers because it is cumbersome and its benefits are only theoretical. However, a very gentle standard technique of enucleation should be employed, without clamping the optic nerve prior to cutting it.
There have been recent advances in the types of orbital implants used following enucleation. The hydroxyapatite implant, designed to improve the ocular motility in patients undergoing enucleation, is still used widely,47,48 but other motility implants have been introduced.
Pre-enucleation radiotherapy (PERT) has been advocated by some authorities. In general, this involves the use of 2000 cGy of external beam radiotherapy to the affected eye and orbit prior to enucleation. Data from the COMS have supported prior non-randomized studies that suggested that PERT is not advantageous over standard enucleation alone.11