Ocular melanoma: total dose and dose rate effects with Co-60 plaque therapy

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.

Incidence of cataract and outcomes after cataract surgery in the first 5 years after iodine 125 brachytherapy in the Collaborative Ocular Melanoma Study: COMS Report No. 27

PURPOSE

To evaluate the effect of the radiation dose to the lens on cataract formation and effect of cataract surgery on visual acuity (VA) among patients with choroidal melanoma treated with iodine 125 (I125) brachytherapy.

DESIGN

Prospective study of patients enrolled in one arm of a randomized clinical trial.

PARTICIPANTS

Patients enrolled in the Collaborative Ocular Melanoma Study (COMS) who received I125 brachytherapy as randomly assigned and also were phakic, with no history of cataract in the study eye at the time of enrollment (n = 532).

METHODS

Each follow-up examination included an interim ocular history and full ophthalmic examination. Lens status (phakic, pseudophakic, or aphakic) and best-corrected VA were recorded. For the purpose of this analysis, the date of the first examination at which an eye was reported to be aphakic or pseudophakic, to have vision-limiting lenticular opacities, or to have had cataract surgery was defined as the observed time of cataract development. Date of cataract surgery was defined as the date of the first follow-up examination at which cataract surgery was reported.

MAIN OUTCOME MEASURES

Incidence of cataract and outcomes after cataract surgery.

RESULTS

During the first 5 years of follow-up, cataracts developed in 362 (68%) of the 532 study eyes, including 49 (9%) that had had cataract surgery. By 5 years, 83% of study eyes were reported to have a cataract (95% confidence interval [CI], 79%-87%), and 12% had undergone cataract surgery (CI, 9%-15%) in the study eye. Eighteen percent of eyes that received a dose of 24 Gy or higher to the lens underwent cataract surgery, whereas only 4% of patients with <12 Gy to the lens underwent cataract surgery. Median VAs were 20/125 before cataract surgery and 20/50 after cataract surgery. After cataract surgery, VA improved by 2 lines or more in 32 (66%) patients and remained stable in 13 (26%) patients. The most common cause of lack of visual improvement after cataract surgery was presence of radiation retinopathy.

CONCLUSION

Although cataract surgery was infrequent among COMS patients, VA remained stable or improved in the majority of these eyes after cataract surgery.

The American Brachytherapy Society recommendations for brachytherapy of uveal melanomas

PURPOSE

This article presents the American Brachytherapy Society (ABS) guidelines for the use of brachytherapy for patients with choroidal melanomas.

METHODS

Members of the ABS with expertise in choroidal melanoma formulated brachytherapy guidelines based upon their clinical experience and a review of the literature. The Board of Directors of the ABS approved the final report.

RESULTS

Episcleral plaque brachytherapy is a complex procedure and should only be undertaken in specialized medical centers with expertise in this sophisticated treatment program. Recommendations were made for patient selection, techniques, dose rates, and dosages. Most patients with very small uveal melanomas (<2.5 mm height and <10 mm in largest basal dimension) should be observed for tumor growth before treatment. Patients with a clinical diagnosis of medium-sized choroidal melanoma (between 2.5 and 10 mm in height and <16 mm basal diameter) are candidates for episcleral plaques if the patient is otherwise healthy and without metastatic disease. A histopathologic verification is not required. Small melanomas may be candidates if there is documented growth; some patients with large melanomas (>10 mm height or >16 mm basal diameter) may also be candidates. Patients with large tumors or with tumors at peripapillary and macular locations have a poorer visual outcome and lower local control that must be taken into account in the patient decision-making process. Patients with gross extrascleral extension, ring melanoma, and tumor involvement of more than half of the ciliary body are not suitable for plaque therapy. For plaque fabrication, the ophthalmologist must provide the tumor size (including basal diameters and tumor height) and a detailed fundus diagram. The ABS recommends a minimum tumor (125)I dose of 85 Gy at a dose rate of 0.60-1.05 Gy/h using AAPM TG-43 formalism for the calculation of dose. NRC or state licensing guidelines regarding procedures for handling of radioisotopes must be followed.

CONCLUSIONS

Brachytherapy represents an effective means of treating patients with choroidal melanomas. Guidelines are established for the use of brachytherapy in the treatment of choroidal melanomas. Practitioners and cooperative groups are encouraged to use these guidelines to formulate their treatment and dose reporting policies. These guidelines will be modified as further clinical results become available.

Stereotactic radiotherapy in the treatment of ocular melanoma: a noninvasive eye fixation aid and tracking system

Ocular melanoma is frequently treated using brachytherapy implants (such as 125I and 60Co plaques or 184Ta wire), surgery, or external beam radiotherapy using small 60Co beams, high energy x-rays, or proton therapy. The last technique, though very expensive, provides improved dose distributions and dose localizations in the treatment of tumours adjacent to critical normal tissues. The technique of fractionated stereotactic radiotherapy is now being used at an increasingly large number of centers in the treatment of lesions in the brain, and the head and neck. This article describes the successful extension of the stereotactic technique to the treatment of ocular melanoma: an eye fixation aid is attached to a noninvasive, relocatable Gill-Thomas-Cosman head frame together with a simple eye-movement tracking system.

Amelanotic choroidal nevus and melanoma: cytology, tumor size, and pigmentation as prognostic indicators

BACKGROUND

Choroidal nevi are fairly common lesions of the posterior pole that can sometimes transform into melanoma, and it is thought that most choroidal melanomas arise from preexisting nevi. Occasionally, these lesions present as nonpigmented or amelanotic variations of their pigmented counterparts. Recent studies suggest a relationship between tumor pigmentation and risk of growth and metastasis, with a better prognosis for lightly pigmented or amelanotic lesions.

CASE REPORTS

A case of an amelanotic choroidal nevus and melanoma are presented. In Case 1, a 26-year-old white female was found to have a large amelanotic nevus in the right eye. After 7 years of periodic observation, the lesion has not changed. In Case 2, a 51-year-old white male was diagnosed with a large amelanotic melanoma in the left eye. Due to extensive involvement of the optic nerve, the patient underwent enucleation. Histological evaluation confirmed the lesion as a mixed-cell type malignant amelanotic melanoma.

CONCLUSION

Management of choroidal nevi generally consists of periodic observation, and the most widely accepted management of choroidal melanoma is observation, radiotherapy, and transpupillary thermotherapy or enucleation. The therapeutic modality of choice for melanoma will vary depending on the size, growth, and location of the lesion. In addition, recent studies suggest an association between heavy tumor pigmentation, tumor size, cell type, and risk of metastasis. Although many variables will influence the final treatment option, pigmentation of the lesion should also be considered.

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.

125I plaque therapy for uveal melanoma. Analysis of the impact of time and dose factors on local control

BACKGROUND

125I episcleral plaque therapy has gained wide acceptance for the treatment of uveal melanoma because of its potential to preserve vision, salvage the globe, and provide good local control. A rigorous analysis of the optimum radiation dose, dose rate, and overall treatment time has not been reported with this technique.

METHODS

One hundred fifty patients with uveal melanoma treated with 125I plaques between 1982 and 1990 and included in the uveal melanoma study (UMS) database of the Wills Eye Hospital were analyzed. Mean patient age was 60.7 years (range: 17.7-84.6 years). Initial mean tumor size was 9.7 x 8.5 x 3.7 mm with a range of 4.5 to 21.5 mm in basal dimension and 1.2 to 11.8 mm in height. Mean dose to the tumor apex was 94.77 gray (Gy) (29.5-141 Gy). Mean dose rate to the tumor apex was 92.9 cGy/hr (10-292 cGy/hr); the mean dose to the base was 359 Gy (181-692 Gy); the mean dose rate to the base was 348 cGy/hr (112-893 cGy/hr); and mean duration of treatment was 124.7 hours (range: 28-333 hours)

RESULTS

With a median follow-up of 68 months, there have been 33 local failures. Mean time to local failure was 19 months (range: 6-78 months). Actuarial local control is 81% at 5 years. Multivariate analysis demonstrates significant correlation of local failure with larger tumor dimension (P = 0.0046), close proximity to the optic disc (P = 0.0029), lower radiation dose to the tumor apex (P = 0.03), lower radiation dose rate to the tumor apex and base (P = 0.01 and 0.03), and longer overall treatment time (P = < 0.0001).

CONCLUSIONS

This retrospective analysis reinforces the importance of dose rate, minimum tumor dose, overall treatment time, maximum tumor basal dimension, and proximity to the optic nerve in the treatment of uveal melanoma.

Single-dose compared with fractionated-dose radiation of the OM431 choroidal melanoma cell line

PURPOSE

To compare single-dose and fractionated-dose radiotherapeutic effects on choroidal melanoma cells.

METHODS

We determined the effects of gamma radiation on OM431 cell survival by exposing cells to either a single 9-Gy dose or two 4.5-Gy fractionated doses at intervals of 20 minutes to eight hours. The effects of single dosing and fractionated dosing at six hours were compared at doses of 2 to 12 Gy.

RESULTS

Tumor cell repair was most rapid during the first two hours. Maximum repair had occurred by six hours after radiation. Cell survival curves showed doses greater than 3 Gy of single-dose gamma radiation resulted in a greater number of cells killed than did equivalent fractionated doses.

CONCLUSIONS

Ocular melanoma in vitro is relatively radioresistant to low-dose fractionated radiotherapy. High single-dose radiotherapy would be more effective but would also result in more damage to normal tissue unless more focused modalities of radiotherapy are used.

Helium ions versus iodine 125 brachytherapy in the management of uveal melanoma. A prospective, randomized, dynamically balanced trial

PURPOSE

Optimal radiation therapy for uveal melanoma is uncertain, and the relative efficacies of radioactive plaques and charged particles are unclear.

METHODS

The authors prospectively studied helium-ion irradiation and iodine 125 (125I) brachytherapy in a randomized, dynamically balanced trial. Of the 184 patients who met the eligibility criteria, 86 were treated with helium ions and 98 with 125I brachytherapy.

RESULTS

No patients with uveal melanoma had a history of systemic malignancy. Tumors were less than 15 mm in maximum diameter and less than 10 mm in thickness. A minimum tumor dose of 70 GyE was delivered to the tumor apex. There was a significantly higher local recurrence rate after 125I brachytherapy than after helium-ion irradiation. Enucleations occurred more frequently after brachytherapy (relative risk = 1.99; 95% confidence interval, 0.78-5.78). More anterior segment complications occurred after helium-ion irradiation. To date, there has been no measurable impact on survival.

CONCLUSIONS

Most uveal melanomas can be managed with radiation with retention of the eye. There was better tumor control with helium-ion irradiation; however, there were more anterior segment complications.

Treatment of choroidal melanoma with I-125 plaque

PURPOSES

To evaluate efficacy of I-125 episcleral plaque therapy in patients with ocular melanoma and determine survival, eventual visual acuity, and complications.

METHODS AND MATERIALS

Between July 1, 1984 and January 1, 1991, 144 patients with diagnosis of ocular melanoma were treated with high activity I-125 episcleral plaques. Tumor volumes ranged from 14 to 3449 mm3. Lesion size included small (n = 15; height < 5 mm, and/or largest basal diameter of 8-16 mm) and large (n = 45; height > 8 mm, and/or largest basal diameter > 16 mm). Apical doses ranged from 74.25 to 83.66 Gy with scleral doses ranging from 41 and 160 Gy. Follow-up has ranged from 25 to 90 months (Med = 46 months).

RESULTS

Ocular survival was noted in 130/144. Reasons for enucleation included progressive tumor growth (n = 4), extrascleral extension (n = 4), or blind/painful eye (n = 6), 94 patients developed complications which included cataract (n = 43), optic neuropathy (n = 12), neovascular glaucoma (n = 8) and retinopathies (n = 31). Visual acuity testing pre-episcleral plaque therapy revealed 102 patients with 20/200 vision; at last follow-up 59 patients demonstrated visual acuity testing of 20/200 or better.

CONCLUSION

The use of episcleral I-125 plaque therapy allows for safe and effective therapy in patients with ocular melanoma of various size depending on location and probable visual acuity outcome. A total apical dose of 75 Gy given at 60-65 cGy/hour provides durable local control with acceptable complication rates.

Choroidoretinal neovascularisation following radon seed treatment of retinoblastoma in two patients

Two patients who developed localised radiation retinopathy many years after brachytherapy for retinoblastoma are described. In both patients extracapsular cataract extraction and YAG laser capsulotomy were followed by preretinal and vitreous haemorrhage and in one patient there was deterioration of existing radiation retinopathy with macular oedema. Premacular and vitreous haemorrhage occurred from focal, preretinal neovascular membranes which appeared to originate from residual choroidal vascular radicals. Laser photocoagulation was successful in ablating preretinal neovascular membranes and limiting the extent of macular oedema from incompetent retinal capillaries adjacent to the atrophic macular scars.