Microwave plaque thermoradiotherapy for choroidal melanoma

Glaucomagenesis following ionizing radiation exposure

Glaucoma is a group of optic neuropathies causing optic nerve damage and visual field defects, and is one of the leading causes of blindness. Nearly a century has passed since the first report of glaucoma manifested following ionizing radiation therapy of cancers. Nevertheless, associations between glaucoma and radiation exposures, a dose response relationship, and the mechanistic underpinnings remain incompletely understood. Here we review the current knowledge on manifestations and mechanisms of radiogenic glaucoma. There is some evidence that neovascular glaucoma is manifest relatively quickly, within a few years after high-dose and high dose-rate radiotherapeutic exposure, but little evidence of excess risks of glaucoma after exposure to much lower doses or dose rates. As such, glaucoma appears to have some of the characteristics of a tissue reaction effect, with a threshold of at least 5 Gy but possibly much higher.

Long-term followup comparing two treatment dosing strategies of (125) I plaque radiotherapy in the management of small/medium posterior uveal melanoma

Objective. To investigate the efficacy of two different dosing strategies of radioactive iodine-125 (¹²⁵I) in the management of small- and medium-sized posterior uveal melanoma. Patients and Methods. The medical records of consecutive patients with choroidal melanomas between 1.5 and 5.0 mm in apical height treated initially with ¹²⁵I plaque radiotherapy were reviewed. Patients were treated with one of the following two treatment dosing strategies: (1) 85 Gy to the apical height of the tumor (group 1) or (2) 85 Gy to a prescription point of 5.0 mm (group 2). Results. Of 95 patients, 55 patients were treated to the apical height of the tumor, and 40 were treated to a prescription point of 5.0 mm. Comparative analysis of the incidence rates of specific complications between the two groups demonstrates that group 2 had a significantly higher incidence of radiation retinopathy, radiation optic neuropathy, and/or visually significant cataract formation than group 1 (P = 0.028). Conclusion. Treatment of choroidal melanomas less than 5 mm in apical height with ¹²⁵I brachytherapy to the true apical height is equally effective when compared to treatment with 85 Gy to 5.0 mm. Treatment to the apical height of the tumor may result in lower incidence of radiation-related complications.

Episcleral plaque 125I radiotherapy with episcleral LCF hyperthermia: a prospective randomized trial

PURPOSE

The purpose of this study was to search for an optimal radiation dose in the treatment of patients with uveal melanoma using 125I episcleral plaque radiotherapy (EPRT) and episcleral hyperthermia (HT).

METHODS AND MATERIALS

From 1991-1998, 35 patients with uveal melanoma were enrolled in a phase II prospective randomized trial of 125I EPRT combined with episcleral HT. Two groups were closely matched for pre-treatment patient and tumor characteristics. Group 1: N = 16, and Group 2: N = 19. The median dose to the tumor apex for Group 1 was 80.0 Gy and 60.8 Gy for Group 2. Episcleral HT was given once for 45 min immediately prior to EPRT with a median temperature of 44 degrees C for both groups. The median follow-up was 5.5 years for Group 1 and 5.3 years for Group 2.

RESULTS

The median tumor height decreased 1.7 mm for patients of both groups. The 5- and 8-year probability of local recurrence was 33% for Group 1, and 25% for Group 2, p = 0.73. The 5-year probability of DFS was 54% for Group 1 and 67% for Group 2, p = 0.51. The 5- and 8-year overall survival was 68% and 34%, respectively, for Group 1, and 83% and 50%, respectively, for Group 2, p = 0.60. The rate of distant metastasis at 5- and 8-years for Group 1 was 29% and 62%, respectively, and 17% and 17%, respectively, for Group 2, p = 0.18. The incidence of enucleation was 4 (25%) in Group 1 vs. 4 (22%) in Group 2. The incidence of late complications was similar in either treatment group. The ambulatory visual acuity (> 5/200) at last follow-up was slightly better in Group 2 (80%) than Group 1 (64%).

CONCLUSIONS

Treatment outcomes were similar despite a 25% difference in radiation dose. In view of these findings and in an attempt to reduce the incidence of late treatment toxicity a still lower radiation dose in combination with HT needs to be studied. The reported outcomes need to be evaluated with caution due to the small number of patients in this study.

Anterior segment tumors: current concepts and innovations

The most common anterior segment tumors are primary neuroepithelial cysts, uveal melanomas, metastatic tumors, and benign tumors. In the majority of cases, the diagnosis can be made utilizing a careful clinical history and ocular examination. Ultrasound examination (low and high frequency) has become an indispensable tool used to determine tumor extension and involvement of the surrounding structures. In particular, high-frequency ultrasound has been used to uncover iris pigment epithelial cysts, to allow for the diagnosis of small ciliary body melanomas, and to measure tumors for plaque radiation planning. Whereas fluorescein angiography and computerized tomography have come to play a limited role, fine-needle aspiration biopsy has been found to be quite helpful in selected cases. Once the diagnosis is established, treatment decisions depend on the tumors' location, size, local extension, patterns of growth, and secondary complications. Most anterior segment tumors can be observed for growth prior to treatment. Other options include local resection (iridectomy, lamellar sclerouvectomy, or eye-wall resection) and radiation (ophthalmic plaque or external beam). Enucleation is typically employed if these eye- and vision-sparing treatments are not possible and for uncontrollable secondary glaucoma. This review examines the unique role of high-frequency ultrasonography for the diagnosis and treatment of anterior segment tumors as well as an overview of clinical practice.

Thermochemotherapy in hereditary retinoblastoma

BACKGROUND/AIM

The combination of chemotherapy and transpupillary thermotherapy, thermochemotherapy (TCT) has become an established part of the treatment plan in advanced retinoblastoma. The aim of this study was to identify safe indications, the complications as well as the limitations of this new treatment for retinoblastoma.

METHODS

Tumour response and side effects of TCT with an indirect laser ophthalmoscope (spot size about 400 micro m) in 55 tumours of 26 children with bilateral retinoblastoma were analysed. Using the Reese-Ellsworth classification system, nine of 35 eyes were classified as type I, 13 eyes as type II, 10 eyes as type III, and three eyes as type V. The mean age of the children was 0.74 (SD 0.61) years. The mean tumour height was 3.5 (2.3) mm with a mean diameter of 6.1 (4.1) mm. Treatment parameters were 4.3 (1.6) (median 5) thermochemotherapy sessions with a mean energy of 539 (211) mW and a mean duration of 13.5 (5.6) minutes. Chemotherapy courses (vincristine, etoposide, and carboplatin) were repeated every 3 weeks. The mean follow up period was 1.25 (0.6) years.

RESULTS

Local recurrence occurred in 21 tumours (38%), with a mean onset of 3.2 (2.9) months after TCT. The risk of tumour recurrence was correlated with tumour height. The recurrence rate was 17% for tumours with a height less than 2 mm, 37% for tumours with a height between 2 and 4 mm, and 63% for larger retinoblastomas. Multivariate analysis identified fish flesh regression after TCT (p = 0.0007) as the most important risk factor for tumour recurrence besides tumour height (p = 0.001) and the necessity of increased laser power during TCT sessions (p = 0.018). Complications during therapy included transient corneal opacification in two eyes (6%), focal iris atrophy (three eyes, 8.5%), peripheral lens opacity (two eyes, 6%), circumscribed transient retinal detachment (one eye, 3%) and diffuse choroidal atrophy (one eye, 3%).

CONCLUSION

TCT using an indirect laser ophthalmoscope with a spot size of about 400 micro m was efficient for retinoblastoma with a tumour height less than 4 mm. In larger tumours, the recurrence rate was unacceptably high. Fish flesh regression after TCT correlates with a higher rate of local tumour recurrence. Treatment related complications occurred in less than 9% of the treated eyes.

Primary transpupillary thermotherapy (TTT) for malignant choroidal melanoma

PURPOSE

To evaluate the efficacy of transpupillary thermotherapy (TTT) as the only method of treatment for small choroidal melanoma.

PATIENTS AND METHODS

In a prospective non-randomized analysis, 20 patients with primary choroidal melanoma (posterior to the equator with base < or = 2 and thickness < or = 4.5 mm) were treated with TTT as the only method of treatment (diode laser at 810 nm, beam diameter 3 mm, power setting 0.3-0.9 W, exposure time 20-37 min). During follow-up of at least 6 months, clinical aspects, ultrasonographic tumour thickness, fluorescein and indocyanine green angiographic patterns, visual acuity and ocular side-effects were recorded.

RESULTS

In 17 eyes the tumour regressed significantly within 3 months after one treatment session (to a flat chorioretinal scar in 15 eyes). Despite a clinically flattened chorioretinal scar, fluorescein and indocyanine green angiography revealed that choriocapillary vessels in the heat-treated areas of 15 eyes remained perfused. Three amelanotic melanomas showed almost no response to TTT after repeated treatment at higher power settings. Visual acuity remained unchanged or improved in 12 eyes. Ocular side-effects included posterior synechia of the iris (1), macular oedema (2) and temporary retrobulbar pain (2). No patient showed tumour recurrence or metastases during follow-up.

CONCLUSIONS

Preliminary results obtained by this study demonstrate good efficacy and visual outcome following TTT as the only method of treatment for small choroidal melanoma. However, indocyanine green angiographic findings suggest that tissue damage in the choroidal layer might be less effective, which perhaps may lead to a higher rate of tumour regrowth. Long-term follow-up is required to obtain data on late ocular side-effects, tumour recurrence and metastasis.

Palladium-103 plaque radiotherapy for choroidal melanoma: results of a 7-year study

OBJECTIVE

To describe the first clinical experience with palladium-103 (103Pd) ophthalmic plaque radiotherapy for choroidal melanoma.

DESIGN

Phase-I (nonrandomized) clinical trial.

PARTICIPANTS

Eighty patients with uveal melanomas were diagnosed by clinical examination, found to be negative for metastatic disease, and offered 103Pd radioactive plaque treatment. Nine patients were concurrently treated with microwave hyperthermia.

INTERVENTION

Palladium-103 ophthalmic plaque radiotherapy was employed for each patient. Eye plaques were sewn to the episclera to cover the base of the intraocular tumor, radiation was continuously delivered over 5 to 7 days, and then the plaques were removed. A mean apical dose of 81 Gy was delivered.

MAIN OUTCOME MEASURES

The authors evaluated the ease of use of 103Pd seeds within standard gold eye plaques. Patient-related outcomes were control of tumor growth, change in visual acuity, the development of radiation damage (retinopathy, optic neuropathy, and cataract), and metastatic disease.

RESULTS

From September 1990 to December 1997, 80 patients were treated with 103Pd and followed for an average of 38 months. Two patients were lost to follow-up. During this time, the authors found that 103Pd seeds were equivalent to iodine-125 (125I) with respect to plaque manufacture and ease of dosimetric calculations. Two patients in this series were treated for tumor recurrence after 125I plaque radiotherapy. They both failed secondary 103Pd treatment and were enucleated. When 103Pd was used as a primary treatment, it controlled the growth of 75 of 78 tumors (96%). Overall, there have been six enucleations: three failures of primary treatment, two failures of retreatment, and one for neovascular glaucoma. Visual acuity evaluations at the 36-month follow-up visit (including the enucleated patients) revealed that 38% of eyes had decreased 3 or more lines of vision, and 77% were 20/200 or better.

CONCLUSION

Palladium-103 plaque radiotherapy can be used to treat uveal melanomas. Compared with 125I, computerized dosimetry suggests a more favorable dose distribution with 103Pd. Treatment of most patients resulted in tumor shrinkage and preservation of functional vision. The authors have noted no complications that might preclude the use of 103Pd ophthalmic plaque radiotherapy for choroidal melanoma.

Clinicopathologic findings in recurrent choroidal melanoma after transpupillary thermotherapy

OBJECTIVE

This study aimed to report the clinicopathologic findings of recurrent choroidal melanoma after transpupillary thermotherapy (TTT).

DESIGN

Two case reports.

METHODS

The clinical histories and ophthalmologic findings of two patients with recurrent choroidal melanomas who did not respond to TTT were reviewed. Both patients had their eyes with the melanoma enucleated and processed routinely for light and electron microscopic examination.

MAIN OUTCOME MEASURES

The eyes were examined for histopathologic and ultrastructural findings.

RESULTS

Histopathologic examination showed choroidal melanomas with extensive tumor necrosis and hemorrhage. In areas, tumor cells appeared histologically intact and presumably viable, with ultrastructural evidence of melanogenesis. The eye from one patient was treated only with TTT and showed hemorrhagic necrosis with cytolysis and no changes to tissues surrounding the melanoma. The eye from the other patient, treated with TTT and a radioactive isotope of iodine (I125) plaque, exhibited areas of intact tumor, tumor necrosis, fibrosis, and radiation retinopathy.

CONCLUSIONS

These two cases among a total treated series of 14 patients represent examples of uveal melanoma regrowth after TTT. Opaque media precluded adequate treatment in the first case that showed some TTT effect. The second case showed a combination of TTT and I125 effect and failed because of the aggressive nature of tumor.

The microcirculation of choroidal and ciliary body melanomas

The microcirculation of ciliary body and choroidal melanomas is remodelled into patterns. The presence of microvascular networks, composed of back-to-back loops that encircle microdomains of tumour, and parallel vessels with cross-linking, are associated with death from metastatic melanoma. The formation of these complex vascular patterns may result from reciprocal interactions between the tumour cell and the extracellular matrix, and pattern formation may reflect an invasive tumour cell phenotype. Ciliary body and choroidal melanomas are among the few forms of cancer treated before a pathologist assigns a grade to indicate whether tumour is likely to follow a benign or aggressive course. There is evidence to suggest that prognostically significant microcirculatory patterns may be detectable by non-invasive imaging techniques that may provide a substitute for biopsy to guide the clinical management of patients with these sight- and life-threatening tumours.

Radiation therapy for choroidal melanoma

Radiotherapy offers patients with malignant melanoma of the choroid an eye and a vision-sparing alternative to enucleation. The most commonly used forms of radiotherapy are ophthalmic plaque brachytherapy and charged-particle (external beam) radiotherapy. Unfortunately, after all forms of radiotherapy for choroidal melanoma many patients experience sight-limiting side effects, and an average of 16.3% of patients treated with radiotherapy subsequently require enucleation because of tumor regrowth or uncontrollable neovascular glaucoma. The severity, location, and incidence of radiation-induced complications are related to the type of radiation used, its method of delivery, amount of radiation delivered to normal ocular structures, the size and location of the tumor, as well as its response to irradiation. Current research is directed toward developing methods to reduce the amount of radiation delivered to normal structures, e.g., adding heat to radiotherapy. The true viability and metastatic potential of irradiated uveal melanoma cells has not been established, although clinical studies have reported local control of choroidal melanoma in 81-100% (mean = 92.8%) of cases. The purpose of this review is to present the world's experience with radiotherapy for choroidal melanoma, information that will contribute to patient education and informed consent.

Microwave thermoradiotherapy for uveal melanoma: results of a 10-year study

OBJECTIVE

The purpose of the study is to evaluate clinically the use of microwave-heating (hyperthermia) as an adjuvant to ophthalmic plaque irradiation for treatment of patients with uveal melanoma. Hyperthermia was also used as a radiation sensitizer, allowing for significant dose reductions during ophthalmic plaque radiation therapy.

PARTICIPANTS

In this case series, 48 patients were treated with microwave plaque thermotherapy for uveal melanoma.

INTERVENTION

Microwave treatment, which involved affixing a miniature microwave dish antenna on the sclera beneath the tumor after completion of plaque brachytherapy, was performed. During hyperthermia treatment, the tumor's apex was targeted to receive a minimum of 42 degrees C for a 45-minute duration. A subset of 38 (79%) were given reduced apical doses of ophthalmic plaque radiation (radioactive isotope of iodine [125I] or palladium-103 [103Pd]) to an average of 52.6 Gy.

MAIN OUTCOME PARAMETERS

Patients were evaluated for visual function, microwave toxicity, radiation oculopathy, eye retention, local tumor control, and metastatic disease.

RESULTS

Patients have been observed for up to 10 years and for an average of 60 months (5 years). To date, there have been 3 cases of postoperative tumor enlargement (growth) for a 93.8% local control rate. Two patients were lost to follow-up. Seven eyes have been enucleated: three due to neovascular glaucoma, one due to uveitic neovascular glaucoma, and three due to progressive tumor enlargement. Although 15 patients have died, only 4 deaths were because of metastatic choroidal melanoma. Of the original 48 patients, 33 (69%) have maintained within 2 lines or have better than their preoperative visual acuity. Side effects attributable to heating have included decreased intraocular pressure without hypotony as well as chorioretinal scar formation within and around the targeted zone.

CONCLUSIONS

The results of this series suggest that adjuvant microwave thermotherapy can be used with reduced doses of ophthalmic plaque radiation therapy to control the growth of uveal melanomas. Although the incidence of neovascular glaucoma, enucleation, and tumor regrowth is comparable to that of other series evaluating radiation alone, the visual acuities of microwave plaque thermotherapy-treated eyes were found to be superior.

Conformal episcleral plaque therapy

PURPOSE

Episcleral plaque therapy (EPT) with sealed 125I sources is widely used in the treatment of choroidal melanoma. In EPT, as elsewhere in radiotherapy, concern for normal tissue tolerance has frequently been a dose-limiting factor. The concept of conformal therapy, which seeks to improve dose homogeneity within the tumor and greatly reduce the dose to uninvolved structures may provide a solution to this problem. Radioactive sources are typically distributed uniformly over the surface of an episcleral plaque and are sometimes offset slightly from the scleral surface to reduce the dose to the sclera relative to the apex and prescribed therapeutic margin at the tumor base. Nevertheless, it is not uncommon for scleral dose to exceed the dose to the apex of intermediate to tall tumors by a factor of 4 or more. The availability of low-energy sealed sources such as 125I prompted the development of gold-backed plaques to shield noninvolved periocular tissues. The concept of shielding can be extended to include collimation of individual sources. The potential advantages of individual source collimation include reduced scleral dose, more homogeneous tumor dose, and superior shielding of adjacent normal structures such as the fovea as compared to previous plaque designs.

METHODS AND MATERIALS

A three-dimensional treatment-planning system has been extended to design a plaque that incorporates individually collimated 125I sources. Thermoluminescent dosimetry (TLD) and radiochromic film were used to compare calculated dose-rate distributions with measured dose rates in an acrylic phantom.

RESULTS

Calculations predict that source collimation in the form of a "slotted" gold plaque will achieve the purposes of the study. The collimating effect of the slots is demonstrated qualitatively using radiochromic film, and the accuracy of the calculation is demonstrated quantitatively with TLD.

CONCLUSION

The episcleral plaque described in this report is simpler to assemble than previous plaque designs. It produces a more homogeneous dose distribution in the tumor, reduces scleral dose by up to 50% as compared to conventional designs, and significantly reduces radiation dose to uninvolved structures adjacent to the plaque.

Ferromagnetic hyperthermia: functional and histopathologic effects on normal rabbit ocular tissue

Ferromagnetic (FM) hyperthermia has previously been evaluated in a rabbit tumour model of ocular melanoma. To study the effect of focal heating in normal rabbit eyes, FM seeds were implanted into a 14-mm episcleral plaque an heated to operating temperatures of 48 or 58 degrees C. Thermal induction was performed by placing rabbits in a uniform, oscillating (11 kHz) magnetic field operating at 1200 W and as H-field strength of 265 A/m. Eyes were heated for 60 min with continuous scleral temperature monitoring. Hyperthermic effects were monitored by direct opthalmic examination, fundus photography, serial electroretinography and histopathology. Intraocular temperatures were mapped with direct fiberoptic thermometry. All treatment effects were confined to the area covered by the episcleral plaque. Direct ophthalmoscopic examination revealed early retinal whitening during heat induction followed by localized exudative retinal detachments, limited to the area of the retinal surface overlying the plaque, that resolved spontaneously. Serial electroretinography was virtually indistinguishable between the 48 and 54 degrees C temperature groups. We noted a minimal alteration in a- and b-wave amplitudes with no changes in implicit times. Histopathology at 3 weeks post-treatment documented chorioretinal scarring overlying the thermal plaque treatment zone. No evidence of heamorrhage infection, cataract or scleral thinning was noted. This study documents the apparent focal containment of thermal effects with FM heating utilizing operating temperatures ad high as 54 degrees C for 60 min, and discloses no evidence of diffuse ocular toxicity.

Brachytherapy in primary ocular tumors

Patients with primary ocular tumors are seen infrequently in the medical profession, and most of these patients are referred to specialty centers which has resulted in a good study population. In the past, ocular tumors were treated with enucleation, but the current emphasis is now on organ preservation with sparing of all or partial visual acuity. In the management of these tumors, plaque brachytherapy and particle beam therapy have been used more frequently as an alternative to enucleation. A multi-institutional study, the Collaborative Ocular Melanoma Study (COMS), is currently underway, organized by the National Eye Institute. The COMS isotope of choice is Iodine-125 (I-125). Recurrence after plaque therapy is approximately 15%, although it may be as high as 37% at 15 years for metastatic disease. In one study, nondiffuse iris melanoma has been controlled in 93% of patients by custom plaques utilizing I-125. Plaque brachytherapy also utilizes I-125 for the treatment of retinoblastoma tumors either as primary therapy or following external beam radiation. Currently, through the utilization of plaque radiation therapy, enucleation may be avoided in the majority of patients, and many patients may retrieve some visual acuity. We will review plaque brachytherapy techniques, diagnosis, staging, and some of the pertinent literature of the two most frequently encountered primary ocular tumors: choroidal melanoma, sometimes referred to as uveal melanoma, with an incidence of approximately 1,500 new cases per year in the adult population; and retinoblastoma, the most common intraocular primary malignancy found in childhood, with a frequency of approximately 250 [corrected] new cases per year.

Histopathological findings in human choroidal melanomas after transpupillary thermotherapy

AIMS

The effect of transpupillary thermotherapy (TTT) on human choroidal melanomas was investigated by means of histopathology.

METHODS

Before enucleation TTT was performed in 11 eyes with a xenon are photocoagulator with a red filter or a diode laser at 810 nm. The exposure time was 1 minute; the estimated temperature at the top of the tumour was about 65 degrees C.

RESULTS

Seven of 11 tumours developed necrosis to a maximum depth of 3.9 mm with a sharp demarcation between the necrotic and the viable part of the tumour. The depth correlated with penetration of heat into the tumour. Scattered small haemorrhages in the transitional zone between the necrotic and the viable part of the tumour were observed in three eyes but large haemorrhages were absent. Ocular media were not affected owing to the low rate of absorption of radiation at 810 nm. TTT did not cause significant scleral damage. Intrascleral tumour cells with a viable appearance were observed in one eye, where the tumour was almost totally necrotic.

CONCLUSION

Results show that TTT has potential as a conservative therapeutic treatment for choroidal melanomas.

Concurrent versus sequential application of ferromagnetic hyperthermia and 125I brachytherapy of melanoma in an animal model

OBJECTIVE

To determine the efficacy of concurrent versus sequential ferromagnetic hyperthermia (FMH), combined with Iodine-125 (125I) brachytherapy, in the treatment of uveal melanoma in a rabbit model.

MATERIALS AND METHODS

A Greene melanoma cell line was implanted in rabbit eyes to establish a tumor model comparable to a uveal melanoma. Seventy-one tumor-containing rabbit eyes were treated with 125I brachytherapy at 20, 25, 35, 45, or 55 Gray (Gy)(38 eyes), and with either concurrent (15 eyes) or sequential (18 eyes) FMH, delivered at 48.2 degrees C for 1 hour. An additional 13 eyes were treated with FMH alone at 48.2 degrees C, either in a single heat application (5 eyes), or in a repetitive mode (8 eyes). The radiation and heat were delivered via an episcleral plaque. All tumors were followed with indirect ophthalmoscopy and echography.

RESULTS

Tumors treated with 125I brachytherapy alone exhibited complete tumor regression in 50% of eyes at 42 Gy with none of the tumors responding to less than 35 Gy. FMH alone at 48.2 degrees C applied in one cycle limited tumor growth in 20% of eyes, while all eyes treated with repetitive heating exhibited complete tumor control. With concurrent application of FMH and 125I, the 50% tumor control rate occurred at 9.5 Gy, thus resulting in a thermal enhancement ratio (TER) of 4.4. With sequential treatment, the 50% tumor control rate was at 30 Gy, with a resultant TER of 1.4. No complications related to 125I brachytherapy were noted in any eyes, while transient retinal whitening was seen with the FMH.

CONCLUSION

This study documents the enhanced synergistic interaction of concurrent FMH and 125I brachytherapy, compared to sequential treatment, in this rabbit melanoma model.

Transpupillary thermotherapy in the management of choroidal melanoma

BACKGROUND

Several methods of treatment have been used for choroidal melanoma. The purpose of this report is to evaluate the effectiveness of transpupillary thermotherapy using near-infrared radiation to treat choroidal melanoma.

METHODS

A prospective study was conducted to evaluate the clinical features, treatment results, and complications of patients with choroidal melanoma who were treated with transpupillary thermotherapy delivered over one to four sessions and followed for at least a 6-month period. All treated tumors had either documentation of growth or ophthalmoscopic risk factors for future growth and/or metastasis.

RESULTS

There were 17 patients with choroidal melanoma treated with transpupillary thermotherapy. The mean tumor size before treatment was 6.6 mm in base and 3.0 mm in thickness. The tumor margin was a mean of 2.3 mm from the optic disc and 2.7 mm from the foveola. Seven tumors (41%) touched the optic disc margin and three (18%) were under the fovea. The tumor responded to treatment in all patients, with a decrease in thickness and resolution of associated subretinal fluid. At a minimum of 6 months of follow-up, the mean tumor thickness was 1.7 mm, and the tumor site was a residual chorioretinal scar with partial visibility of the sclera in all patients. Despite the proximity to the optic disc and foveola, the final visual acuity was the same or improved in ten eyes (59%) and decreased in seven (41%). The improved vision was due to resolution of subfoveal fluid, whereas the decreased vision was primarily the result of treatment in the fovea with ultimate retinal vascular occlusion or preretinal traction. Although long-term follow-up is not yet available, there were no patients with tumor recurrence or tumor metastases.

CONCLUSIONS

This preliminary study demonstrates that transpupillary the thermotherapy appears to be an effective treatment for selected small choroidal melanomas and may be a particularly useful modality for treating those tumors near the foveola and optic disc. Longer follow-up is necessary to assess for local recurrence and the impact of treatment on survival.

Posterior uveal melanoma. The Swedish perspective

Posterior uveal melanoma is the most common primary intraocular malignant tumour and in Sweden some 70-80 new cases present each year. While uveal melanoma is more prevalent in the setting of ocular melanocytosis and neurofibromatosis, there is little conclusive data on the aetiology. Most patients experience a progressive visual field defect and present with a grey or greyish-brown mass of the posterior choroid. Diagnostic procedures include fluorescein angiography, ultrasound and magnetic resonance imaging. In some cases, intraocular biopsy may be required to make a correct diagnosis. Posterior uveal melanomas can usually be managed by any of a number of eye-preserving options like plaque radiotherapy and charged particle irradiation, but eyes containing large tumours are often enucleated. Nearly half of patients with posterior uveal melanoma, and in particular those with large tumours, ultimately succumb to metastatic disease. While most patients with tumour dissemination are treated with systemic chemotherapy possibly combined with interferon, metastatic spread confined to the liver may potentially be managed by intraarterial perfusion chemotherapy or liver resection. However, outcome of patients with systemic disease remains extremely poor with a median survival following detectable tumour dissemination of only two to five months. There are still insufficient data on the impact of various treatments on survival, but a large prospective trial addressing this issue is in progress. The present review summarizes the state-of-the-art knowledge and current management of posterior uveal melanoma from a Swedish perspective.

Adenocarcinoma of the retinal pigment epithelium: a diagnostic and therapeutic challenge

BACKGROUND

Adenocarcinoma of the retinal pigment epithelium (RPE) is an uncommon intraocular tumor which has been rarely if ever diagnosed prior to enucleation. Our review of the literature suggests that when a melanotic and tuberous-shaped tumor presents in a woman with signs of uveitis one should consider the diagnosis of adenocarcinoma of the RPE.

METHODS

We report a case in which a 4.9-mm-tall, mushroom-shaped, moderately reflective melanotic tumor found to be present in a 50-year-old woman. Other findings included a 12 x 10-mm dense transillumination shadow and 270 deg of posterior iris synechiae. With a presumptive diagnosis of uveal melanoma the patient was treated with palladium-103 plaque radiotherapy. Within 6 months she underwent enucleation due to uncontrollable ocular pain and progressive tumor growth. Histopathologic evaluation revealed an adenocarcinoma of the (RPE).

RESULTS

Two months after radiotherapy the eye developed acute angle-closure glaucoma, secondary retinal detachment, and a painful scleritis (a result similar to that of Greer, who treated an intraocular adenoma with radiation). Our diagnosis of adenocarcinoma of the RPE was made after enucleation.

CONCLUSION

Adenocarcinomas of the RPE are rarely if ever diagnosed on clinical evaluation, should be suspected in women with a melanotic intraocular tumor and uveitis, and may respond poorly to ophthalmic plaque radiotherapy. All reported cases presenting without extrascleral extension have not metastasized.

Microwave thermoradiotherapy for intraocular melanoma

We evaluated the use of microwave hyperthermia as an adjuvant to ophthalmic plaque radiotherapy for patients with intraocular tumors. Forty-eight patients were offered combined microwave plaque thermoradiotherapy (TRT) as a primary treatment for their uveal melanomas. A dish-shaped microwave antenna was placed on the sclera beneath the tumor at the time of plaque brachytherapy. While temperatures were measured at the sclera, the tumor's apex was targeted to receive a minimum of 42 degrees C for a 45-min duration. Patients were also given full or reduced doses of plaque radiotherapy (125I or 103Pd). We reduced the minimum tumor radiation dose (apex dose) for 42 (88%) of our patients to <70 Gy (mean, 52.5 Gy). The 48 TRT patients were followed for < or =8 years (average, 45 months). To date, there has been one documented postoperative tumor enlargement, for a 97.2% local control rate. Two patients were lost to follow-up. Four eyes have been enucleated: two due to neovascular glaucoma, one to glaucoma secondary to intraocular inflammation, and one for progressive tumor enlargement. Although 13 patients have died, only four deaths were due to metastatic melanoma. Thirty-five patients (73%) have maintained within two lines or had better than their preoperative visual acuity. Side effects attributable to heating included chorioretinal scar formation within and around the targeted zone and decreased intraocular pressures without hypotony. Our experience with this heat delivery system suggests that adjuvant microwave thermotherapy can be used with plaque radiotherapy for the treatment of uveal melanoma.

Radiation therapy for subretinal neovascularization

PURPOSE

To evaluate low-dose external beam irradiation and plaque radiotherapy for the treatment of subretinal neovascularization.

METHODS

The authors treated 137 patients with radiation therapy for subretinal neovascularization. Herein, they examine a subset of 75 patients with exudative age-related macular degeneration who were treated with (4- or 6-MV photons) external beam irradiation at a dose of 1200 to 1500 cGy to the affected macula. In addition, six patients were treated with palladium 103 ophthalmic plaque brachytherapy to an equivalent retinal apex dose of 1200 to 1500 cGy. The authors compared the intralesional, intraocular, and intracranial radiation dose distributions of each treatment modality. Early Treatment Diabetic Retinopathy Study-type visual acuity determinations, ophthalmic examinations, and angiography were performed before and after treatment. Clinical evaluations were performed in a nonrandomized and unmasked fashion.

RESULTS

Episcleral plaque brachytherapy was found to provide a higher average radiation dose within the neovascular tissues while delivering less radiation to most normal ocular (both eyes) and all intracranial structures. Both forms of radiotherapy were associated with decreased hemorrhages, exudates, and leakage of neovascular membranes. Ten (13 percent) patients receiving external beam radiotherapy had transient epiphora and ocular irritation.

CONCLUSION

Observation and laser photocoagulation of subfoveal neovascularization have been associated with poor visual outcomes. Pilot experience suggests that low-dose radiotherapy offers a method to treat subretinal neovascularization without destroying the overlying retina. Although the authors' radiation distribution studies favored plaque radiotherapy, additional factors such as relative efficacy, expense, convenience, and safety must be investigated.

Episcleral plaque thermoradiotherapy of posterior uveal melanomas

Episcleral plaque radiotherapy is a widely applied treatment for selected patients with uveal melanomas. This treatment is well tolerated but may produce severe late radiation complications resulting in decreased visual acuity that reduces the attractiveness of conservative therapy. The purpose of this study was to access if the addition of episcleral hyperthermia decreases late radiation complications through radiation dose reduction while maintaining high incidence of local tumor control. In a 3-year period, episcleral plaque thermoradiotherapy was given to 25 patients with uveal melanoma in a Phase I study. The mean tumor height was 6.2 mm and the mean tumor basal area was 173 mm(2). The mean radiation dose given to the tumor apex was 72.2 Gy and the mean hyperthermia temperature, given once for 45 min, was 43.5 degrees C. Of the 25 patients treated, 22 (88%) showed tumor height reduction, 2 (8%) showed no change, and 1 (4%) had an increase in tumor height. At the last follow-up (range, 20-68 months; mean, 31.2 months), a 43% mean tumor height reduction was recorded (p = 0.0002). Of the 22 patients initially showing tumor regression, 2 (9%) had subsequent tumor progression. At least ambulatory vision (>5/200) was maintained by 20 (80%) patients. Severe complications, including hemorrhagic retinal detachment and a large vitreous hemorrhage, were seen in 2 (8%) patients early in this Phase I study. The treatment program was well tolerated by the study patients. Severe late treatment toxicity was sharply reduced by limiting the mean scleral temperature to < or equal to 44 degrees C. This study employing 30% lower radiation doses, showed tumor regression in the majority of patients. Longer follow-up is needed to assess long-term treatment efficacy and late treatment complications.

Microwave cyclodestruction: evaluation on human eyes

AIMS

The study was set up to evaluate the effect of microwave cyclodestruction on human eyes.

METHODS

Two human eyes were studied. For treatment a horn shaped 5.8 GHz microwave applicator and fibre optic thermometry were used. Just before enucleation, the rectangular (2 x 3 mm) microwave aperture was placed onto the conjunctiva at a position 1-2 mm posterior to the corneal scleral limbus. Each of three to four treatment spots was targeted to receive a thermal dose of 54 degrees C for 1 minute. Clinical, gross, and histopathological evaluations were performed.

RESULTS

Clinical evaluations of the treatment sites (immediately after microwave application) revealed no evidence of conjunctival or scleral damage. Trace fluorescein 2% uptake was noted within the targeted zones. The first eye was sectioned along the equatorial axis. Examination of the ciliary body and pars plana revealed whitening of the ciliary processes and depigmentation. Histopathological evaluations revealed ciliary epithelial necrosis with pigment dispersion. The vascularity of the ciliary processes showed focal disruption and haemorrhage. The underlying ciliary muscle and sclera appeared to be unaffected. No other findings could be attributed to microwave cyclodestruction.

CONCLUSION

The results of this phase I toxicity study suggest that microwave heating can be used to damage preferentially the epithelial layers of the human ciliary body.

Palladium 103 plaque radiotherapy for uveal melanoma. Clinical experience

PURPOSE

To evaluate the effect of palladium 103(103Pd) ophthalmic plaque brachytherapy on patients with uveal melanoma.

BACKGROUND

Radioactive 103Pd seeds have become available for plaque brachytherapy, and computer-aided simulations have compared the intraocular dose distribution of 103Pd versus iodine 125 (125I) plaques in patients with uveal melanoma. The use of the lower-energy radionuclide 103Pd increased the radiation to the tumors and decreases irradiation of most normal ocular structures.

METHODS

The authors have begun a phase 1 clinical trial evaluating the effect of 103Pd ophthalmic plaque radiotherapy on intraocular tumors. Uveal melanoma was diagnosed, and the patients were found to be negative for metastatic disease. All patients were given one 103Pd radioactive plaque treatment, and six patients also were given adjuvant microwave hyperthermia.

RESULTS

Palladium 103 ophthalmic plaque radiotherapy was used to treat 23 patients with uveal melanoma. Patients were followed for up to 27 months (mean, 13.5 months). One eye was enucleated for progressive tumor enlargement (4 months after treatment). One patient died (of metastatic melanoma). Eight patients have lost greater than two lines of visual acuity, one has gained more than two lines. Fifteen patients (65%) were within two lines or had better than their preoperative visual acuity. Relating to the effect of treatment on visual acuity, 15 (65%) tumors were located equal to or less than 2 mm from the fovea.

CONCLUSION

Palladium 103 ophthalmic plaque radiotherapy was noted to control the growth of uveal melanomas. Compared with other forms of plaque radiotherapy at this follow-up interval, the authors have noted no new complications, no difference in local control, and/or changes in tumor response to treatment. More long-term follow-up will be required to demonstrate differences between 125I and 103Pd ophthalmic plaque brachytherapy.

Palladium-103 versus iodine-125 for ophthalmic plaque radiotherapy

PURPOSE

A dosimetry study comparing the use of I-125 vs. Pd-103 radioactive seeds for ophthalmic plaque brachytherapy.

METHODS AND MATERIALS

Palladium-103 (Pd-103) seeds in ophthalmic plaques were used to treat 15 patients with intraocular malignant melanoma. Computer-aided simulations were performed to evaluate the intraocular dose distribution of I-125 versus Pd-103 ophthalmic plaques (delivering equivalent apex doses). Seven target points were selected. Starting at the outer scleral surface, four were located along the central axis of the plaque: the 1 mm point (the inner sclera), the 6 mm point, the tumors apex, and the opposite eye wall. We also evaluated the fovea, optic nerve, and the lens because they were considered to be critical structures.

RESULTS

These studies demonstrated that the lower energy photons generated by Pd-103 seeds (average 21 KeV) in ophthalmic plaques were more rapidly absorbed in tissue than photons generated by I-125 (average 28 KeV). Therefore, during ophthalmic plaque radiotherapy, Pd-103 photons were found to be more rapidly absorbed within the tumor and less likely to reach most normal ocular structures. On average, the use of Pd-103 decreased the dose to the fovea by 5.7%, to the optic nerve by 8.4%, to the lens by 26%, and to the opposite eye wall by 38.4%.

CONCLUSION

Palladium-103 ophthalmic plaque brachytherapy resulted in slightly more irradiation of the tumor and less radiation to most normal ocular structures.

Retrobulbar oedema after ophthalmic plaque radiotherapy

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