Episcleral radioactive plaque therapy: initial clinical experience with 56 patients

Transitioning from a COMS-based plaque brachytherapy program to using eye physics plaques and plaque simulator treatment planning system: A single institutional experience

The aim of this work is to describe the implementation and commissioning of a plaque brachytherapy program using Eye Physics eye plaques and Plaque Simulator treatment planning system based on the experience of one institution with an established COMS-based plaque program. Although commissioning recommendations are available in official task groups publications such as TG-129 and TG-221, we found that there was a lack of published experiences with the specific details of such a transition and the practical application of the commissioning guidelines. The specific issues addressed in this paper include discussing the lack of FDA approval of the Eye Physics plaques and Plaque Simulator treatment planning system, the commissioning of the plaques and treatment planning system including considerations of the heterogeneity corrected calculations, and the implementation of a second check using an FDA-approved treatment planning system. We have also discussed the use of rental plaques, the analysis of plans using dose histograms, and the development of a quality management program. By sharing our experiences with the commissioning of this program this document will assist other institutions with the same task and act as a supplement to the recommendations in the recently published TG-221.

Dosimetric and radiobiologic comparison of 103Pd COMS plaque brachytherapy and Gamma Knife radiosurgery for choroidal melanoma

PURPOSE

Plaque brachytherapy (BT) and Gamma Knife radiosurgery (GKRS) are highly conformal treatment options for choroidal melanoma. This study objectively compares physical dose and biologically effective dose (BED) distributions for these two modalities.

METHODS AND MATERIALS

Tumor and organ-at-risk (OAR) dose distributions from a CT-defined reference right eye were compared between ¹⁰³Pd COMS (Collaborative Ocular Melanoma Study Group) plaques delivering 70 Gy (plaque heterogeneity corrected) over 120 h to the tumor apex and GKRS plans delivering 22 Gy to the 40% isodose line for a representative sample of clinically relevant choroidal melanoma locations and sizes. Tumor and OAR biologically effective dose-volume histograms were generated using consensus radiobiologic parameters and modality-specific BED equations.

RESULTS

Published institutional prescriptive practices generally lead to larger tumor and OAR physical doses from COMS BT vs. GKRS. Radiobiologic dose conversions, however, revealed variable BEDs. Medium and large tumors receive >1.3 times higher BEDs with COMS BT vs. GKRS. OAR BEDs have even greater dependence on tumor size, location, and treatment modality. For example, COMS BT maximum BEDs to the optic nerve are lower than from GKRS for large anterior and all posterior tumors but are higher for anterior small and medium tumors.

CONCLUSIONS

BT and GKRS for choroidal melanoma have different physical dose and BED distributions with potentially unique clinical consequences. Using published institutional prescriptive practices, neither modality is uniformly favored, although COMS BT delivers higher physical doses and BEDs to tumors. These results suggest that lowering the physical prescription dose for COMS BT to more closely match the BED of GKRS might maintain equivalent tumor control with less potential morbidity.

I-125 brachytherapy for choroidal melanoma photographic and angiographic abnormalities: the Collaborative Ocular Melanoma Study: COMS Report No. 30

OBJECTIVES

(1) To summarize the protocol used for grading features of postradiation abnormalities from fundus photographs and fluorescein angiograms of patients enrolled in the Collaborative Ocular Melanoma Study (COMS); (2) to document the prevalence of features of interest in the posterior pole of these eyes during 8 years of follow-up; and (3) to investigate baseline patient, tumor, and treatment characteristics associated with posterior pole features.

DESIGN

Observational case series within a randomized, multicenter clinical trial.

PARTICIPANTS

We evaluated 650 patients who were assigned to and received iodine-125 brachytherapy in the COMS for medium-sized tumors.

METHODS

Color fundus photographs and fluorescein angiograms were taken at baseline and 2, 5, and 8 years; 30 features were graded according to a standard protocol.

MAIN OUTCOME MEASURES

Prevalence at selected time intervals of fundus photographic features associated with retinopathy and optic neuropathy.

RESULTS

The percentage of patients with >/=1 feature of interest was 49.2% at baseline, 84.4% at 2 years, 91.2% at 5 years, and 90.7% at 8 years. The most frequent findings across all follow-up examinations were macular microaneurysms (75.6% of examinations), macular angiographic leakage (75.1%), and optic disc hyperfluorescence (62.8%). The median number of features present increased significantly with each follow-up to a maximum of 7 features at 8 years. The prevalence of neovascularization of the disc at 5 years was 5.2%. The prevalence of optic neuropathy at 5 years was 27.4%. Prognostic factors for more prevalent and severe posterior pole abnormalities were diabetes, tumor location close to both optic nerve and foveal avascular zone, and greater dose of radiation to the foveola and optic nerve head.

CONCLUSIONS

The amount and severity of retinopathy and optic neuropathy after iodine-125 brachytherapy increased through 8 years of follow-up. Assessment of photographs and angiograms taken in accord with a standard protocol provided reliable estimates of rates of development of features of retinopathy and optic neuropathy in eyes treated using the COMS brachytherapy protocol. Our findings support earlier reports that tumor factors in addition to radiation treatment may contribute to posterior pole abnormalities.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any materials discussed in this article.

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.

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.

Custom-made "Nag" eye plaques for 125I brachytherapy

PURPOSE

To report our experience in treating medium-size ocular melanomas with custom-made "Nag" eye plaques.

METHODS

Seventy-eight patients with medium-size ocular melanomas were treated with plaques of 0.6-mm-thick, 18k gold with a radius of curvature of 12 mm to conform to the curvature of the eyeball. These plaques were custom-made in various sizes and shapes to encompass the base of the tumor and a 1-mm margin on all sides. Apertures in three wings of these plaques allowed sutures to be easily placed to hold the plaques onto the sclera. A dose of 100 Gy (before TG-43) or 85 Gy (after TG-43) was delivered with (125)I in 4 days. The dose was prescribed to the periphery of tumor at the level of tumor apex to ensure that the entire tumor volume received at least this dose.

RESULTS

The median follow-up was 49 months (range 8-112 months). The progression-free survival (Kaplan-Meier method), overall survival, and disease-specific survival at 5 years were 93%, 86%, and 97%, respectively. Fifty of 78 (64%) patients retained useful visual acuity (20/200 or better). Thirty-one of 78 (40%) patients developed retinopathy or papillopathy. In the subgroup of 22 patients with tumor distance < or =2 mm from optic disc or macula, 12 patients (54%) developed retinopathy or papillopathy. Only 7 of these patients (32%) had useful vision (20/200 or better). Short distance to optic disc or macula was associated with significantly poor visual acuity and moderate to severe retinopathy or papillopathy (ANOVA, p = 0.004 and p = 0.002, respectively).

CONCLUSION

Our experience suggests that custom-made Nag plaque brachytherapy can control medium-size choroidal melanoma and that a 1-mm, rather than the standard 2-mm, minimum margin is sufficient when this plaque and prescription methods are used. Patients with tumors close (< or =2 mm) to optic disc or macula have a significantly poorer visual outcome.

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.

Radioactive plaque therapy for metastatic choroidal carcinoma

PURPOSE

To describe the outcome of radioactive episcleral plaque therapy for treatment of metastatic carcinoma to the choroid.

DESIGN

Retrospective, noncomparative case series.

PARTICIPANTS

Five patients (six eyes) with carcinoma metastatic to the choroid.

METHODS

Retrospective review of the clinical records of five patients (six eyes) who underwent radioactive episcleral plaque therapy for choroidal metastases.

MAIN OUTCOME MEASURES

Tumor height, visual acuity, radiation optic neuropathy, and radiation retinopathy.

RESULTS

Radioactive episcleral plaque therapy resulted in shrinkage of the treated tumors and resolution of subretinal fluid in all eyes. After plaque treatment, best-corrected visual acuity was maintained within two lines of initial visual acuity for two eyes, decreased more than two lines for one eye, and improved more than two lines in three eyes. The treatment was well tolerated and there was no acute toxicity. Late complications included optic nerve atrophy (at 2 years) with proliferative radiation retinopathy (at 3 years) in one eye and optic atrophy (at 6 months) in another eye that had received prior external beam therapy.

CONCLUSIONS

In carefully selected cases, radioactive episcleral plaque therapy appears to be an effective and reasonable treatment for carcinoma metastatic to the choroid.

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.

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.

Management of stage I malignant melanoma

BACKGROUND

Because of the rising incidence of melanoma, dermatologists are increasingly responsible for diagnosing and managing patients with this cutaneous malignancy. Fortunately, with the increased awareness and emphasis on early detection, most patients will present with tumors that have not yet spread beyond their primary focus in the skin (ie, Stage I). Dermatologists must, therefore, be fully versed in the diagnosis and management of Stage I melanoma.

OBJECTIVE

This review article focuses on the most important issues related to the diagnosis and management of Stage I melanoma. An emphasis will be placed on surgical management.

RESULTS

The mainstay of therapy for most patients with Stage I melanoma is surgery. The important principles of diagnostic biopsy and surgical excision will be discussed. There are several additional modalities that may be useful as adjuvants to surgical therapy or as primary therapy in situations when surgery is not feasible. Those include elective lymph node dissection, hyperthermic isolation limb perfusion, radiotherapy, cryotherapy, chemotherapy, and immunotherapy. These will all be reviewed.

CONCLUSIONS

With a thorough understanding of the important principles and controversies related to the management of Stage I melanoma, dermatologists can effectively manage the growing number of patients with this malignancy.

Concordance for Hodgkin's disease in identical twins suggesting genetic susceptibility to the young-adult form of the disease

BACKGROUND

Relatives of young adults with Hodgkin's disease are at increased risk of Hodgkin's disease, and lines of evidence implicate both inheritance and environment.

METHODS

We have identified and followed 432 sets of twins affected by Hodgkin's disease. The number of cases of Hodgkin's disease observed before the age of 50 years in the healthy monozygotic and dizygotic twins of the patients with Hodgkin's disease was compared with the number expected from national age-specific incidence rates.

RESULTS

None of the 187 pairs of dizygotic twins became concordant for Hodgkin's disease, whereas 10 of the 179 pairs of monozygotic twins did; in 5 of these pairs, the second case appeared after the original ascertainment. During the observation period, 0.1 (monozygotic) and 0.1 (dizygotic) cases in the unaffected twins were expected. Monozygotic twins of patients with Hodgkin's disease thus had a greatly increased risk (standardized incidence ratio, 99; 95 percent confidence interval, 48 to 182), whereas no increase in the risk for dizygotic twins of patients with Hodgkin's was observed.

CONCLUSIONS

Genetic susceptibility underlies Hodgkin's disease in young adulthood.

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.

Long-term results of iodine 125 irradiation of uveal melanoma

The authors report on 64 of the first 65 patients treated with iodine 125. The mean follow-up was 64.9 months. After treatment, 29 patients (45.3%) retained visual acuity of 20/100 or better, and 18 patients (28.1%) retained visual acuity within two lines of visual acuity before irradiation. Eleven patients (17.2%) died of metastasis, and 5 patients (7.8%) had local recurrence. Cataract developed in 29 (45.3%) patients; keratitis developed in only 2 (3.1%) patients, and dry eye developed in none. Neovascular glaucoma developed in 7 (10.9%) patients, and 15 (23.4%) patients had radiation retinopathy. Eleven patients (17.2%) required enucleation for either tumor growth or neovascular glaucoma. These results show the increasing number of radiation complications seen with long-term observation and the frequently seen adverse visual outcome.

Episcleral plaque radiotherapy in the treatment of uveal melanomas

During an 8-year period, 85 patients with uveal melanomas were treated with episcleral plaque radiotherapy (EPRT). The T-stage was: T1-3 (4%), T2-29 (34%) and T3-53 (62%). The mean tumor elevation was 6.1 mm. Radiation dose was prescribed at the tumor apex and at D5mm. The mean D5mm dose was 150.1 Gy (range 70.5-430 Gy) and the mean dose at the apex was 102.6 Gy (range 29.8-200 Gy). Useful vision (greater than 5/200) was maintained in 73% of patients. The 5-year actuarial survival was 88%. Metastatic disease developed in 9 (11%) patients, 6 of whom died of their disease. Basal tumor dimensions were important factors predicting metastatic disease, p = 0.002. A decrease in tumor evaluation was seen in 82%. There was a much lower incidence of decrease in tumor radial and circumferential dimensions, 47.5 and 46%, respectively, p less than 0.001. Treatment complications were common (56%), particularly in patients with large tumors (72%), p = 0.04. The incidence of complications was higher in patients treated prior to 1988 as compared to those who were treated more recently (67 vs 35%, p = 0.010). There were 13 (15%) patients who had enucleation. This included 12 treated before 1986 and 1 patient treated subsequently (46 vs 2%, p less than 0.001). In a univariate analysis, tumor height and radiation dose at D5mm were important factors predicting enucleation, p = 0.004. In a multivariate analysis, however, the most important factor predicting enucleation was treatment administration prior to 1986, p less than 0.001). A sharp decrease in the incidence of severe complications, including enucleation, as seen after 1985, is likely due to a major effort in treatment optimization.

Combined localized current field hyperthermia and irradiation for intraocular tumors

Ten patients with large melanomas and one patient with recurrent retinoblastoma were treated with combined localized current field (LCF) hyperthermia and iodine 125 irradiation delivered by episcleral plaque. Tumors were heated to 43 degrees to 45 degrees C for 28 to 45 minutes. Localized current field hyperthermia when combined with irradiation appeared to induce rapid tumor necrosis. One eye enucleated 17 hours after treatment showed only focal necrosis of the melanoma, while another eye demonstrated extensive necrosis 60 hours after treatment. In all remaining eyes, tumor regression occurred within the first month of treatment. Complications included cataract formation in six eyes, hemorrhagic retinal detachment in five eyes, and phthisis in two eyes. Complications from combined therapy of large intraocular tumors in this series appeared to result from the rapid necrosis of the tumor and secondary intraocular inflammation. Intraocular temperature dosimetry measurements demonstrated a temperature gradient of not more than -0.23 degrees C/mm-1 per axial millimeter from the episcleral plaque surface to the apex of the tumor. The authors believe that LCF hyperthermia could be a suitable means of application of hyperthermia in patients with intraocular tumors if further modifications were performed to reduce ocular complications.