Palladium-103 versus iodine-125 for ophthalmic plaque radiotherapy

I-125 eye-plaque seed economics: To re-use or to not re-use? A single institutional cost savings analysis of re-using I-125 radioactive seeds for eye-Plaque brachytherapy

INTRODUCTION

Iodine-125 (I-125) seeds, commonly used in low-dose rate brachytherapy for ocular malignancies, are often discarded after a single use. This study examines the potential cost savings at an institution with high ocular melanoma referrals, by re-using I-125 seeds for eye-plaque brachytherapy.

METHODS

In this single-institutional retrospective analysis, data was collected from I-125 seed orders from 8/2019 through 10/2022. Information including number of seeds ordered per lot, number of plaques built per lot, and number of seeds used per lot were collected. Cost per lot of seed was assumed to be the current cost from the most recent lot of 35 seeds.

RESULTS

During the study, 72 I-125 seed lots were ordered bi-weekly, with a median of 35 seeds per lot (Range: 15-35). Each seed was used on average 2.26 times prior to being discarded. The average duration of each seed lot used was 62.2 days (Range: 21-126). Each seed lot contributed to the construction of an average of 8.4 eye plaques (Range: 2-20). With seed recycling, 2,475 seeds were used to construct 608 eye-plaques. Without re-using practice this would require 5,694 seeds. This resulted in a percentage cost savings of 56.5%, with a total seed cost reduction of $344,884, or $559 per eye-plaque on average.

CONCLUSION

This is the first study to evaluate cost savings relative to re-using I-125 seeds for eye plaques. The data demonstrates how an institution can decrease costs associated with I-125 radiation seeds used for eye-plaque brachytherapy by re-using them.

Exclusive Ru-106 brachytherapy for the management of a recurrent corneo: Conjunctival squamous cell carcinoma

BACKGROUND

We report a case of personalized exclusive brachytherapy treatment for the management of a highly recurrent squamous cell conjunctival carcinoma with corneal invasion.

CASE DESCRIPTION

This is a case of a Caucasian 81-years-old man who presented 10 years ago to our clinic with a pink-white para-limbal mass with dilated feeder arteries and mild leukoplakia. Excisional biopsy confirmed the presence of conjunctival intraepithelial neoplasia (CIN). Successively, he underwent two 4-weeks cycles of Mytomicin C topical therapy and a second excisional surgery, due to several recurrences of the lesion. At the last relapse, the pink-white peri-limbic mass which invaded the corneal limbus, determining corneal opacification from 5- to 7-clock hours, was confirmed by anterior segment optical coherence tomography (AS-OCT). Due to resistance to MMC therapy and chronic epitheliopathy, an AS-OCT guided exclusive radiotherapy plan was set: a Rhutenium-106 CCD plaque was applied directly over the afflicted corneal surface, the corneal limbus and the neighboring sclera for 24 hours. The remission of both conjunctival and corneal malignancy was complete 2 months after surgery and no signs of recurrence were highlighted at AS-OCT analysis at the 2-year follow up.

CONCLUSION

Brachytherapy treatment showed optimal management of both corneal and conjunctival involvement, with a free-of-disease follow-up of 24-months. This result suggests that, in specific conditions, Ru-106 brachytherapy could be an effective option of treatment even if not associated with surgical excision.

AAPM recommendations on medical physics practices for ocular plaque brachytherapy: Report of task group 221

The American Association of Physicists in Medicine (AAPM) formed Task Group 221 (TG-221) to discuss a generalized commissioning process, quality management considerations, and clinical physics practice standards for ocular plaque brachytherapy. The purpose of this report is also, in part, to aid the clinician to implement recommendations of the AAPM TG-129 report, which placed emphasis on dosimetric considerations for ocular brachytherapy applicators used in the Collaborative Ocular Melanoma Study (COMS). This report is intended to assist medical physicists in establishing a new ocular brachytherapy program and, for existing programs, in reviewing and updating clinical practices. The report scope includes photon- and beta-emitting sources and source:applicator combinations. Dosimetric studies for photon and beta sources are reviewed to summarize the salient issues and provide references for additional study. The components of an ocular plaque brachytherapy quality management program are discussed, including radiation safety considerations, source calibration methodology, applicator commissioning, imaging quality assurance tests for treatment planning, treatment planning strategies, and treatment planning system commissioning. Finally, specific guidelines for commissioning an ocular plaque brachytherapy program, clinical physics practice standards in ocular plaque brachytherapy, and other areas reflecting the need for specialized treatment planning systems, measurement phantoms, and detectors (among other topics) to support the clinical practice of ocular brachytherapy are presented. Expected future advances and developments for ocular brachytherapy are discussed.

Comparative outcomes and toxicities for ruthenium-106 versus palladium-103 in the treatment of choroidal melanoma

For the treatment of choroidal melanoma, palladium-103 (Pd) and ruthenium-106 (Ru) plaque brachytherapy shows reduced toxicity compared with the historical standard iodine-125. No report has directly compared the clinical outcomes between Pd and Ru, and the reasons for the selection of one over the other remain purely theoretical. Patients with choroidal melanoma with apical tumor height up to 5 mm were included. Patients from Emory University were treated with Pd between 1993 and 2012. Patients from Cleveland Clinic were treated with Ru between 2005 and 2010. Medical records were retrospectively reviewed. We compared post-treatment visual acuity (VA), toxicity, and oncologic outcomes. Pd patients (n=124) and Ru patients (n=42) had a median follow-up of 4.2 and 5.0 years, respectively. Radiation retinopathy-free survival was similar for both radioisotopes, but Ru had lower grades of retinopathy (P=0.006). Pd was associated with worse VA preservation (≥20/40) by year 3 (odds ratio: 3.8; 95% confidence interval: 1.01-14.31, P=0.048). Pd was associated with higher distant metastases-free survival (DMFS) in multivariate analysis (hazard ratio: 0.10; 95% confidence interval: 0.02-0.38; P<0.001). Ru had lower grades of radiation retinopathy and improved long-term VA preservation, but also inferior DMFS, compared with Pd. Because of the inherent limitations of a retrospective analysis, the significance of the inferior DMFS for Ru remains unclear, although the suggestion of a slight inferiority in terms of DMFS for Ru is consistent with the other limited literature. On the basis of this study, we believe that both radioisotopes remain appropriate for the treatment of small choroidal melanomas up to 5 mm in apical height.

A comparison of the shielding effectiveness of silicone oil vitreous substitutes when used with Palladium-103 and Iodine-125 eye plaques

PURPOSE

Episcleral eye plaques provide excellent local control of ocular melanoma, but vision sparing remains a significant problem with 30% or more of patients experiencing significant visual acuity degradation. The use of silicone oil shielding with Iodine-125 plaques has previously been reported to improve critical structure sparing. We hypothesized that the use of Palladium-103 would improve the shielding effectiveness of silicone oil due to the strong energy dependence of the photoelectric effect. This Monte Carlo simulation study reports a comparison of the shielding effects of silicone oil when used in conjunction with Pd-103 and with I-125 plaques.

MATERIALS AND METHODS

GEANT4 was used to simulate eye plaque treatments to an eye with either water-equivalent vitreous humor, or silicone oil in place of the vitreous humor. Two solid gold plaques, 15 and 23 mm, were simulated loaded with I-125 and with Pd-103 source seeds. Seed activity was normalized such that 85 Gy was delivered to the tumor apex in the water-equivalent cases. Tumor apex dose, central axis dose, and inner sclera dose reductions with silicone oil were evaluated.

RESULTS

Silicone oil resulted in an underdosing to the tumor apex of 6.1% and 7.5% in the 15 mm plaque for I-125 and Pd-103, respectively, and 3.4% and 4.3% in the 23 mm plaque for I-125 and Pd-103, respectively. When renormalized to 85 Gy to the tumor apex in all scenarios, silicone oil reduced the dose to the inner sclera 90° from the plaque by 19-32% for the 15 and 23 mm plaques using I-125, and by 33-65% for the 15 and 23 mm plaques using Pd-103.

CONCLUSIONS

The combination of silicone oil and Pd-103 eye plaques offers the potential for greatly improved sparing to normal structures compared to Pd-103 plaques alone or I-125 plaques with or without silicone oil.

Regression patterns of choroidal melanoma: After palladium-103 (103Pd) plaque brachytherapy

Purpose:

To describe the patterns of regression of choroidal melanoma after treatment with plaque brachytherapy.

Methods:

Retrospective interventional case series including 170 consecutive patients treated with ¹⁰³Pd eye plaque radiation for choroidal melanoma. Outcome measures were changes in tumor thickness, surface characteristics, tumor vascularity, ultrasonography, fluorescein angiography, optical coherence tomography, and histopathology.

Results:

The mean initial tumor thickness was 3.9 mm (median 2.8 mm; range 2–11.3 mm) that decreased to 1.7 mm (median 1.2 mm; range 0–7.1 mm) after plaque brachytherapy. On imaging, tumors were pigmented in 51% (n = 86/170), amelanotic in 10% (n = 17/170), and variably pigmented in 39% (n = 67/170). Tumor pigmentation increased in 64% (n = 106/166), decreased in 18% (n = 30/166), and was unchanged in 18% (n = 30/166). Of the 120 that demonstrated intrinsic vascularity, 10% (n = 12/120) had decreased tumor-related vascularity and 90% (n = 108/120) showed complete resolution. Subretinal fluid was present in 34% (n = 58/170) of eyes at presentation. Of them, 15% (9; n = 9/58) had persistent SRF at last follow-up. On ultrasound imaging, 88% (n = 149/170) tumors presented with low to moderate internal reflectivity of which 61% (n = 91/149) showed increased reflectivity on regression. We noted a crescendo–decrescendo fluctuation in the presence of orange pigment lipofuscin along with complete resolution of drusenoid retinal pigment epithelial detachments. In the entire series of 170 patients, there was 0.5% (1) failure of local control, 2% (4) secondary enucleations, and 6% (10) patients developing metastasis.

Conclusion:

Findings related to choroidal melanoma regression after ¹⁰³Pd plaque brachytherapy included decreased intrinsic tumor vascularity, decreased tumor-related subretinal fluid, increased pigmentation, specific changes in orange pigment lipofuscin and resolution of drusenoid retinal pigment epithelial detachments, as well as decreased tumor thickness with an increase in internal reflectivity on ultrasound.

Brachytherapy for patients with uveal melanoma: historical perspectives and future treatment directions

Surgical management with enucleation was the primary treatment for uveal melanoma (UM) for over 100 years. The Collaborative Ocular Melanoma Study confirmed in 2001 that globe-preserving episcleral brachytherapy for UM was safe and effective, demonstrating no survival difference with enucleation. Today, brachytherapy is the most common form of radiotherapy for UM. We review the history of brachytherapy in the treatment of UM and the evolution of the procedure to incorporate fine-needle-aspiration biopsy techniques with DNA-and RNA-based genetic prognostic testing.

Palladium-103 plaque radiation therapy for ciliary body melanoma through a functioning glaucoma filtering bleb

PURPOSE

To provide a clinical description of the long-term outcome of a ¹⁰³Pd plaque-irradiated ciliary body melanoma with extrascleral extension while attempting to preserve a subadjacent glaucoma filtering bleb.

METHODS

A 75-year-old woman with pseudoexfoliative glaucoma for 17 years, 16 years status post argon laser trabeculoplasty, and 15 years status post trabeculectomy in the left eye, was diagnosed with an ipsilateral ciliary body melanoma with visible extrascleral extension. Treatment involved insertion of a ¹⁰³Pd radioactive plaque over the functioning trabeculectomy, with removal 7 days later. At plaque insertion, amniotic membrane grafts were used to cover the plaque and protect the filtering site.

RESULTS

The tumor was successfully treated without clinical evidence of harm to the filtering bleb, with resultant stable intraocular pressure. However, the patient developed blebitis 1.5 years later. Though it resolved with topical antibiotic therapy, the bleb became less succulent. Two years postoperatively, she developed a spontaneous hyphema that resolved after one injection of transscleral bevacizumab 1.25 mg. Her tumor continually regressed in thickness. Without additional glaucoma surgery, her intraocular pressure remained well-controlled on topical medications for 6 years.

CONCLUSIONS

Ciliary body melanoma with minimal extrascleral extension beneath a functioning filtering bleb can be treated using radioactive plaque therapy. In this case, we were able to achieve both tumor regression and glaucoma control by covering the plaque with an amniotic membrane graft.

Visual acuity, oncologic, and toxicity outcomes with 103Pd vs. 125I plaque treatment for choroidal melanoma

PURPOSE

To evaluate outcomes of choroidal melanoma patients treated with ¹²⁵I or ¹⁰³Pd plaque brachytherapy.

METHODS AND MATERIALS

From 1993 to 2012, our institution treated 160 patients with ¹⁰³Pd (56.1%) and 125 patients with ¹²⁵I (43.9%) plaque brachytherapy. Tumor outcomes, visual acuity (VA), and toxicity were compared. Multivariate analyses (MVAs) and propensity score analysis were used to help address differences in baseline characteristics.

RESULTS

Median followup was longer for ¹²⁵I patients, 52.7 vs. 43.5 months (p < 0.01). At baseline, ¹⁰³Pd patients had lower rates of VA worse than 20/200 (4.4% vs. 16%, p = 0.002), T3-T4 tumors (17.5% vs. 32.8%, p = 0.03), and transpupillary thermotherapy use (3.1% vs. 9.6%, p = 0.001). Both ¹⁰³Pd and ¹²⁵I provided >90% 3-year overall survival and >93% 5-year secondary enucleation-free survival. On MVA, radionuclide was not predictive for tumor outcomes. A higher percentage maintained vision better than 20/40 with ¹⁰³Pd (63% vs. 35%, p = 0.007) at 3 years. MVA demonstrated ¹⁰³Pd radionuclide (odds ratio [OR]: 2.12, p = 0.028) and tumor height ≤5 mm (OR: 2.78, p = 0.017) were associated with VA better than 20/40. Propensity score analysis matched 23 ¹²⁵I with 107 ¹⁰³Pd patients. ¹⁰³Pd continued to predict better VA at 3 years (OR: 8.10, p = 0.014). On MVA for the development of VA worse than 20/200 or degree of vision loss, radionuclide was not significant. Lower rates of radiation retinopathy were seen with ¹⁰³Pd than ¹²⁵I (3 years: 47.3% vs. 63.9%, p = 0.016), with radionuclide significant in MVA.

CONCLUSIONS

Both ¹²⁵I and ¹⁰³Pd achieve excellent tumor control. An increased probability of long-term VA better than 20/40 and reduced risk of radiation retinopathy is associated with ¹⁰³Pd.

Context for Protons as Adjunctive Therapy in Neovascular Age-Related Macular Degeneration: A Review

In the last few years we have witnessed increasing availability of proton therapy in the United States and worldwide. As a result, proton therapy is considered as either a primary or adjunctive approach for numerous indications where conventional radiation therapy shows promise but is accompanied by toxicities. Age-related macular degeneration (AMD) remains the leading cause of adult blindness in industrialized nations, and third worldwide, following cataract and glaucoma. Current standard therapy is intravitreal injection of anti-vascular endothelial growth factor agents. While this treatment shows improvement and stabilization in visual acuity for 40% of patients, 60% still experience disease progression. These injections are costly, necessitate repeated office visits, and carry the risk of endophthalmitis. The pathophysiology underlying neovascular AMD (nAMD) underscores the need to simultaneously target multiple pathways to retain useful vision. Radiation can be antiangiogenic, anti-inflammatory, and antiproliferative. Early photon therapy clinical trials were heterogeneous, and a Cochrane review of data demonstrated usefulness in treatment of nAMD but recommended further studies. Advantages of proton therapy over photon therapy include the ability to deliver a focal dose to the target while minimizing dose to normal structures, which is enhanced by unique treatment planning software that uses fluorescein angiography to verify target location and allows conformation of dose to the irregular shape and thickness characteristic of choroidal neovascular membranes, the pathognomonic finding in nAMD. Preliminary data suggest a potential role for proton therapy in the treatment of nAMD. In this article we review previous treatments for AMD, including those with both photon and proton radiation, and recommend future directions for clinical investigations to evaluate the role of proton therapy as an adjunct to antiangiogenic therapy, the current standard of care in this challenging setting.

103Pd versus 125I ophthalmic plaque brachytherapy: preoperative comparative radiation dosimetry for 319 uveal melanomas

Objective

This study was conducted to compare the relative, clinical intraocular dose distribution for palladium-103 (¹⁰³Pd) versus iodine-125 (¹²⁵I) ophthalmic plaque radiation therapy.

Methods

Preoperative comparative radiation dosimetry was performed to evaluate 319 consecutive uveal melanomas treated between 2006 and 2012.

Results

There were 68 (21.3 %) anterior (iris and/or ciliary body) and 251 (78.7 %) choroidal melanomas examined in this study. According to AJCC staging, 7th edition, 146 (45.8 %) were T1, 126 (39.5 %) T2, 40 (12.5 %) T3, and 7 (2.2 %) T4. All were prescribed an equivalent tumor-apex dose. When compared to ¹²⁵I, ¹⁰³Pd was associated with a mean 41.9 % lower radiation dose to the opposite eye wall (p < 0.001), 12.7 % to the lens center (p < 0.001), 7.5 % to the optic disc (p = 0.008), and a 3.8 % decrease to the fovea (p = 0.034). However, subgroup analysis of smaller (T1-staged) tumors showed greater dose reductions to normal ocular structures compared to larger (T4-staged) tumors. Tumor and therefore plaque location also affected intraocular dose distribution. For example, palladium-103-related dose reductions to the fovea, optic nerve, and opposite eye wall were significantly greater for iris and ciliary body tumors compared to posterior choroidal melanomas (p < 0.001). After comparative dosimetry, 98.7 % (n = 315/319) were treated with ¹⁰³Pd.

Conclusion

Preoperative comparative radiation dosimetry was performed for a large cohort of patients with uveal melanoma. It influenced radionuclide selection, offered an opportunity for radiation sparing of critical vision-related intraocular structures, and typically increased radiation within the tumors.

Dosimetry of (125)I and (103)Pd COMS eye plaques for intraocular tumors: report of Task Group 129 by the AAPM and ABS

Dosimetry of eye plaques for ocular tumors presents unique challenges in brachytherapy. The challenges in accurate dosimetry are in part related to the steep dose gradient in the tumor and critical structures that are within millimeters of radioactive sources. In most clinical applications, calculations of dose distributions around eye plaques assume a homogenous water medium and full scatter conditions. Recent Monte Carlo (MC)-based eye-plaque dosimetry simulations have demonstrated that the perturbation effects of heterogeneous materials in eye plaques, including the gold-alloy backing and Silastic insert, can be calculated with reasonable accuracy. Even additional levels of complexity introduced through the use of gold foil "seed-guides" and custom-designed plaques can be calculated accurately using modern MC techniques. Simulations accounting for the aforementioned complexities indicate dose discrepancies exceeding a factor of ten to selected critical structures compared to conventional dose calculations. Task Group 129 was formed to review the literature; re-examine the current dosimetry calculation formalism; and make recommendations for eye-plaque dosimetry, including evaluation of brachytherapy source dosimetry parameters and heterogeneity correction factors. A literature review identified modern assessments of dose calculations for Collaborative Ocular Melanoma Study (COMS) design plaques, including MC analyses and an intercomparison of treatment planning systems (TPS) detailing differences between homogeneous and heterogeneous plaque calculations using the American Association of Physicists in Medicine (AAPM) TG-43U1 brachytherapy dosimetry formalism and MC techniques. This review identified that a commonly used prescription dose of 85 Gy at 5 mm depth in homogeneous medium delivers about 75 Gy and 69 Gy at the same 5 mm depth for specific (125)I and (103)Pd sources, respectively, when accounting for COMS plaque heterogeneities. Thus, the adoption of heterogeneous dose calculation methods in clinical practice would result in dose differences >10% and warrant a careful evaluation of the corresponding changes in prescription doses. Doses to normal ocular structures vary with choice of radionuclide, plaque location, and prescription depth, such that further dosimetric evaluations of the adoption of MC-based dosimetry methods are needed. The AAPM and American Brachytherapy Society (ABS) recommend that clinical medical physicists should make concurrent estimates of heterogeneity-corrected delivered dose using the information in this report's tables to prepare for brachytherapy TPS that can account for material heterogeneities and for a transition to heterogeneity-corrected prescriptive goals. It is recommended that brachytherapy TPS vendors include material heterogeneity corrections in their systems and take steps to integrate planned plaque localization and image guidance. In the interim, before the availability of commercial MC-based brachytherapy TPS, it is recommended that clinical medical physicists use the line-source approximation in homogeneous water medium and the 2D AAPM TG-43U1 dosimetry formalism and brachytherapy source dosimetry parameter datasets for treatment planning calculations. Furthermore, this report includes quality management program recommendations for eye-plaque brachytherapy.

Radiation therapy for neovascular age-related macular degeneration

In the enormity of the public health burden imposed by age-related macular degeneration (ARMD), much effort has been directed toward identifying effective and efficient treatments. Currently, anti-vascular endothelial growth factor (VEGF) injections have demonstrated considerably efficacy in treating neovascular ARMD, but patients require frequent treatment to fully benefit. Here, we review the rationale and evidence for radiation therapy of ARMD. The results of early photon external beam radiation therapy are included to provide a framework for the sequential discussion of evidence for the usage of stereotactic radiation therapy, proton therapy, and brachytherapy. The evidence suggests that these 3 modern modalities can provide a dose-dependent benefit in the treatment of ARMD. Most importantly, preliminary data suggest that all 3 can be used in conjunction with anti-VEGF therapeutics, thereby reducing the frequency of anti-VEGF injections required to maintain visual acuity.

Palladium-103 ophthalmic plaque radiation therapy for choroidal melanoma: 400 treated patients

PURPOSE

To describe 18 years of experience with palladium-103 ((103)Pd) ophthalmic plaque brachytherapy.

DESIGN

Retrospective case series.

PARTICIPANTS

From 1990 to 2007, 400 patients were diagnosed with uveal melanoma, found negative for metastatic disease, and treated. Episcleral (103)Pd radiation was delivered to a mean apical radiation dose of 73.3 Gy over 5 to 7 continuous days.

INTERVENTION

Palladium-103 ophthalmic plaque brachytherapy.

MAIN OUTCOME MEASURES

Patients were evaluated for local tumor control, visual acuity, radiation damage (retinopathy, optic neuropathy, cataract), and metastatic disease.

RESULTS

A total of 272 tumors (68%) were located at or posterior to the equator. There were 186 (46.5%) T1 tumors, 156 (39%) T2 tumors, 50 (12.5%) T3 tumors, and 8 (2%) T4 tumors. Patients were followed for a maximum of 205 months (mean, 51.1 months). Fourteen patients required secondary enucleation (5 for tumor growth and 9 for glaucoma pain control). The local control rate was 96.7%. Life table analysis of patients with 20/200 or better before treatment (n = 357) suggests that 79% and 69% are expected to retain that acuity for 5 and 10 years, respectively. Life table analysis demonstrates a probability that 92.7% and 86.6% of patients will be free of metastatic disease at 5 and 10 years, respectively.

CONCLUSIONS

In a nonrandomized phase I clinical evaluation, (103)Pd ophthalmic plaque radiotherapy was used to treat 400 patients with uveal melanoma. In this series, results after (103)Pd ophthalmic plaque radiotherapy were superior to those reported for alternative forms of radiation.

Design and dosimetric considerations of a modified COMS plaque: The reusable “seed-guide” insert

The Collaborative Ocular Melanoma Study (COMS) developed a standardized set of eye plaques that consist of a 0.5 mm thick bowl-like gold alloy backing with a cylindrical collimating lip. A Silastic seed carrier into which 125I seeds are loaded was designed to fit within the backing. The carrier provides a standardized seed pattern and functions to offset the seeds by 1.0 mm from the concave (front) surface of the carrier. These Silastic carriers have been found to be difficult to load, preclude flash sterilization, and are a source of dosimetric uncertainty because the effective atomic number of Silastic is significantly higher than that of water. The main dosimetric effect of the Silastic carrier is a dose-reduction (compared to homogeneous water) of approximately 10%-15% for 125I radiation. The dose reduction is expected to be even greater for 103Pd radiation. In an attempt to improve upon, yet retain as much of the familiar COMS design as possible, we have developed a thin "seed-guide" insert made of gold alloy. This new insert has cutouts which match the seed pattern of the Silastic carrier, but allows the seeds to be glued directly to the inner surface of the gold backing using either dental acrylic or a cyanoacrylate adhesive. When glued directly to the gold backing the seeds are offset a few tenths of a millimeter further away from the scleral surface compared to using the Silastic carrier. From a dosimetric perspective, the space formerly occupied by the Silastic carrier is now assumed to be water equivalent. Water equivalency is a desirable attribute for this space because it eliminates the dosimetric uncertainties related to the atomic composition of Silastic and thereby facilitates the use of either 125I and/or 103Pd seeds. The caveat is that a new source of dosimetric uncertainty would be introduced were an air bubble to become trapped in this space during or after the surgical insertion. The presence of air in this space is modeled and the dosimetric impact discussed. Another unintended consequence of water equivalency is that some fluorescent x rays emitted from the gold backing can now reach the eye. These very low energy x rays were virtually eliminated by absorption in Silastic. When loaded with 125I seeds the modified plaque appears to produce dose distributions that are almost the same as those of the original COMS plaque and the maximum dosimetric uncertainty introduced by an air bubble is about 2%. Dose distributions calculated for a modified plaque loaded with 103Pd seeds show that dose to healthy ocular structures distal to the tumor apex can be reduced compared to 125I. Clearly, it is faster and easier to glue seeds into the reusable gold seed-guide insert than it is to load the COMS-Silastic carrier.

Laser photocoagulation for radiation retinopathy after ophthalmic plaque radiation therapy

AIM

To evaluate the use of scatter laser photocoagulation to prevent radiation related retinopathy, maculopathy, and loss of vision.

METHODS

This was an interventional case series. 66 eyes with posterior choroidal melanomas treated by ophthalmic plaque radiation therapy were reported. Of these patients, 50 were selected because they developed radiation retinopathy; 45 of these were treated with sector scatter laser photocoagulation to regress clinically evident radiation retinopathy. 16 additional patients (considered to be "high risk" to develop radiation retinopathy) were also treated.

RESULTS

Radiation retinopathy was noted to appear at a mean interval of 26 months following plaque treatment. Laser photocoagulation regressed radiation retinopathy in 29 (64.4%) of the 45 patients treated after the onset of radiation retinopathy (17 with only retinopathy, 10 with a combination of retinopathy and maculopathy, and two with only maculopathy). Of the 16 patients who received laser treatment before clinical evidence of retinopathy, one developed radiation maculopathy and two retinopathy without maculopathy (all three responded to additional laser photocoagulation). In the 45 patient group, vision loss of more than three lines was attributable to radiation maculopathy in seven (15.5%). None of the patients in the prophylactic laser group lost more than three lines of vision as a result of maculopathy.

CONCLUSION

Sector scatter argon laser photocoagulation induced regression of radiation retinopathy. Though early treatment of radiation retinopathy appears to be more effective, a more long term and prospective randomised study will be needed to prove efficacy.

Improved treatment planning for COMS eye plaques

PURPOSE

A recent reanalysis of the Collaborative Ocular Melanoma Study (COMS) medium tumor trial concluded that incorporating factors to account for anisotropy, line source approximation, the gold plaque, and attenuation in the Silastic seed carrier into the dose calculations resulted in a significant and consistent reduction of calculated doses to structures of interest within the eye. The authors concluded that future eye plaque dosimetry should be "performed using the most up-to-date parameters available." The reason these factors are important is attributable to the low energy (125)I radiation (approximately 28 keV) that is primarily absorbed by the photoelectric process. Photoelectric absorption is quite dependent on the atomic composition of the absorbing material. Being 40% silicon by weight, the effective atomic number of Silastic is significantly greater than that of water. Although the AAPM TG43 brachytherapy formalism inherently addresses the issues of source anisotropy and geometry, its parameter that accounts for scatter and attenuation, the radial dose function g(r), assumes that the source is immersed in infinite homogeneous water. In this work, factors are proposed for (125)I that correct for attenuation in the Silastic carrier and scatter deficits resulting from the gold plaque and nearby air. The implications of using (103)Pd seeds in COMS plaques are also discussed.

METHODS AND MATERIALS

An existing TG43-based ophthalmic plaque planning system was modified to incorporate additional scatter and attenuation correction factors that better account for the path length of primary radiation in the Silastic seed carrier and the distance between the dose calculation point and the eye-air interface.

RESULTS

Compared with homogeneous water, the dose-modifying effects of the Silastic and gold are greatest near the plaque surface and immediately adjacent to the plaque, while being least near the center of the eye. The calculated dose distribution surrounding a single (125)I seed centered in a COMS 20 mm plaque was found to be consistent with previously published examples that used thermoluminescent dosimetry measurements and Monte Carlo methods. For fully loaded 12 and 20 mm plaques, calculated dose to critical ocular structures ranged from 16%-50% less than would have been reported using the standard COMS dose calculation protocol.

CONCLUSIONS

Treatment planning for COMS eye plaques that accurately accounts for the presence of the gold, Silastic and extraocular air is both possible and practical.

The design and the dosimetry of bi-nuclide radioactive ophthalmic applicators

A novel type of applicator for the treatment of intra-ocular tumors has been developed, based on the two radionuclides 106Ru/106Rh and 125I. The dose distribution of this ophthalmic plaque combines advantageous features of both radionuclides and can be optimally adapted to a tumor thickness in the range 6.5-9 mm, a size which is beyond the dosimetric limitations of the 106Ru/106Rh plaque therapy. Compared with 125I plaques a bi-nuclide plaque allows to maintain the tumor dosage while the dose in the irradiated volume outside of the target volume is significantly reduced. Consequently, radiosensitive structures within the eye can be spared more effectively. Dedicated methods have been developed for the dosimetry of this plaque. These methods are based on our own extensive dosimetric investigations with plastic scintillators. The precondition was the availability, developed in recent years, of a more accurate determination of the absolute dose rate to water of beta- and low energy emitters.

Palladium-103 plaque radiation therapy for macular degeneration: results of a 7 year study

AIM

To report 7 year results of ophthalmic plaque radiotherapy for exudative macular degeneration.

METHODS

In a phase I clinical trial, 30 patients (31 eyes) were treated with ophthalmic plaque irradiation for subfoveal exudative macular degeneration. Radiation was delivered to a mean 2 mm from the inner sclera (range 1.2-2.4) prescription point calculated along the central axis of the plaque. The mean prescription dose was 17.62 Gy (range 12.5-24) delivered over 34 hours (range 18-65). Early Treatment Diabetic Retinopathy Study (ETDRS) type standardised visual acuity determinations, ophthalmic examinations, and angiography were performed before and after treatment. Clinical evaluations were performed in a non-randomised and unmasked fashion.

RESULTS

At 33.3 months (range 3-4), 17 of 31 (55%) eyes had lost 3 or more lines of vision on the ETDRS chart, five (16%) had improved 3 or more lines, and the remaining nine (29%) were within 2 lines of their pretreatment visual acuity measurement. Overall, 45% of patients were within or improved more than 2 lines of their initial visual acuity. Five eyes developed macular scars, eight developed subsequent neovascularisation or haemorrhage, and three progressed through therapy. Two patients were lost to follow up. The most common finding of patients followed for 6 or more months (n=18 of 29 (62%)) was regression or stabilisation of the exudative process. No radiation retinopathy, optic neuropathy, or cataracts could be attributed to irradiation.

CONCLUSION

Ophthalmic plaque radiation can be used to treat exudative macular degeneration. At the dose and dose rates employed, most patients experienced decreased exudation or stabilisation of their maculas. No sight limiting radiation complications were noted during 7 year follow up. Owing to the variable natural course of this disease, a prospective randomised clinical trial should be performed to evaluate the efficacy of plaque radiation therapy for exudative macular degeneration.

Transscleral resection versus iodine brachytherapy for choroidal malignant melanomas 6 millimeters or more in thickness

OBJECTIVE

To assess differences in treatment outcome after transscleral resection (TSR) and iodine brachytherapy (IBT) of choroidal melanomas too thick for ruthenium brachytherapy.

DESIGN

Matched case-control study.

SETTING

Two national ocular oncology services.

PARTICIPANTS

Forty-nine pairs of patients with choroidal melanoma 6 mm thick or more (range = 6-14), treated within 3 years of each other by either TSR or IBT, and retrospectively matched by age, visual acuity at diagnosis, largest basal tumor diameter, and posterior extension of the tumor.

INTERVENTION

Iodine brachytherapy in Finland or TSR in United Kingdom. Prospectively collected time-to-event data were compared with parametric Weibull regression, adjusting for matching.

MAIN OUTCOME MEASURES

Tumor control, complications, and visual acuity.

RESULTS

Risk of local recurrence after IBT was smaller than that after TSR (hazard ratio [HR] = 0.02, 95% confidence interval [CI] = 0.01-0.11, P<0.001, Weibull regression adjusted for matching), but the 8-year all-cause and melanoma-specific (HR = 0.81, 95% CI = 0.30-2.22, P = 0.69) survivals did not differ. The risks of cataract (HR = 2.05, 95% CI = 1.08-3.89, P = 0.029), maculopathy (HR = 2.28, 95% CI = 0.96-5.43, P = 0.062), and vitreous hemorrhage (HR = 2.30, 95% CI = 0.95-5.57, P = 0.064) were higher after IBT. Rubeosis, neovascular glaucoma, and optic neuropathy developed only after IBT. Risk of retinal detachment, exudative after IBT and rhegmatogenous after TSR (HR = 0.84, 95% CI = 0.40-1.75, P = 0.63), and risk of losing 20/60 vision (HR = 1.37, 95% CI 0.76-2.45, P = 0.29) were comparable between the groups, but risk of losing 20/200 vision was higher after IBT (HR = 2.38, 95% CI = 1.48-3.83, P<0.001). No overall difference in quality of life was found.

CONCLUSIONS

This study suggests that TSR preserves 20/200 vision better than IBT and avoids some of its major complications, but increases the risk of local recurrence. About 350 patients would need to be randomized to prove that TRS preserves 20/60 vision better than IBT.

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.

A reanalysis of the Collaborative Ocular Melanoma Study Medium Tumor Trial eye plaque dosimetry

PURPOSE

To recalculate the radiation doses delivered to structures of interest within the eye, i.e., the lens, tumor apex, 5-mm point, optic disk, and macula for patients treated with eye plaque radiotherapy on the Collaborative Ocular Melanoma Study (COMS) Medium Tumor Trial, using updated dosimetric data.

METHODS AND MATERIALS

Using the Plaque Simulator planning system, doses were recalculated for a sampling of COMS patients for each plaque size. Dosimetry parameters incorporated into the recalculation were line source approximation, a 90% Silastic transmission factor, and a 0% gold transmission factor. Generic solutions were generated from the dose recalculations for each plaque size and structures of interest combination. Doses for the remainder of the patient population were recalculated using the generic solutions and compared with the originally reported COMS doses.

RESULTS

Doses to all structures of interest were reduced 7%-21%, depending on the plaque size and structure combination. The reduction in dose for the macula, optic disc, lens, tumor apex, and 5-mm point was on average 10%, 18%, 8%, 11%, and 12%, respectively. The closer the macula and optic disk were to the plaque rim, the greater the dose reduction. Incorporation of the Silastic transmission factor accounted for a large part of the dose reduction.

CONCLUSIONS

Incorporating anisotropy, line source approximation, and Silastic and gold shield attenuation into dose recalculations resulted in a significant and consistent reduction of doses to structures of interest within the eyes.

Palladium-103 plaque radiotherapy for choroidal melanoma: an 11-year study

PURPOSE

To describe 11 years of experience with 103Pd ophthalmic plaque brachytherapy for intraocular melanoma.

METHODS AND MATERIALS

Since 1990, 152 patients have been diagnosed with uveal melanoma, found to be negative for metastatic disease, and treated with 103Pd radioactive plaque radiotherapy. This study presents the first 100 patients treated with 103Pd and followed for > or = 2 years. Plaques were sewn to the episclera to cover the base of the intraocular tumor. Treatment involved delivery of a mean apical radiation dose of 80.5 Gy during 5-7 days' continuous treatment. Patients were evaluated for local tumor control, visual acuity, radiation damage (retinopathy, optic neuropathy, cataract), and metastatic disease.

RESULTS

Patients in this series were followed for a mean of 4.6 years (55.4 months). 103Pd seeds were found to be equivalent to 125I with respect to plaque manufacture and ease of dosimetric calculations. We noted a local control rate of 96% and six secondary enucleations. Including the enucleated patients, the visual acuity evaluations revealed that 35% lost six or more lines of vision and 73% had vision of 20/200 or better.

CONCLUSION

Long-term results now exist describing the use of 103Pd plaque radiotherapy for uveal (iris, ciliary body, and choroidal) melanoma. Compared with the results from centers using 125I, patients in this series experienced equivalent local control rates and better visual function.

Plaque radiation therapy for malignant melanoma of the iris and ciliary body

PURPOSE

To report on plaque radiation therapy for malignant melanomas involving the iris and ciliary body.

METHODS

Twenty-two eyes (22 patients) with anterior uveal melanomas were treated with (103)Pd ophthalmic plaque radiation therapy. Transillumination and ultrasonography were used to evaluate ciliary body involvement and posterior iris extension. Plaques were placed onto the cornea to treat the anterior tumor margins. The targeted-zone included the tumor and a 2 to 3 mm tumor-free margin. After plaque removal, patients were examined at 1 day, 7 days, 4 weeks, and then every 3 to 6 months thereafter. Systemic evaluations for possible metastatic disease were performed every 6 months.

RESULTS

After plaque radiation therapy, the melanomas decreased in thickness (mean 47%) in all 22 eyes, and no secondary enucleation was performed. One patient died of metastatic melanoma 5 years after radiation therapy. Despite anterior plaque placement that covered portions of the cornea, no epiphora, eyelash loss, or visually significant corneal opacities were noted. Whereas 15 of 21 phakic eyes (71%) developed secondary cataract, no eyes developed ischemic or neovascular radiation maculopathy. Four eyes were noted to have glaucoma before treatment, and two developed it after irradiation. Twenty of 22 eyes (91%) were within 2 lines of their pretreatment visual acuity. After radiation, the mean +/- SD follow-up was 56 +/- 34.4 months (range, 9 to 117 months).

CONCLUSIONS

Plaque radiotherapy of melanomas involving the iris and ciliary body resulted in excellent local control with preservation of vision. Although there was high incidence of secondary cataracts, (103)Pd plaque radiation therapy resulted in no visually significant corneal opacity or radiation retinopathy.

Chemotherapy for eye cancer

Chemotherapy has been used to treat a multitude of eye cancers. We attempted to review the role of chemotherapy in the treatment of ocular, adnexal, and orbital malignancies by conducting an extensive search of the medical literature. Unfortunately, the published reports typically contain few patients with limited follow-up, precluding definitive recommendations. For most eye cancers, multicenter trials will offer the potential to gather the numbers of patients required to determine the clinical utility of chemotherapy.

Tumour location affects the incidence of cataract and retinopathy after ophthalmic plaque radiation therapy

AIM

To examine how tumour location affects ocular morbidity after ophthalmic plaque radiotherapy for uveal melanoma.

METHODS

69 eyes were irradiated and followed for a mean 42 months. There were 23 anterior uveal melanomas and 46 were posterior to the equator. Anterior and posterior tumours had similar basal dimensions. Their mean apical heights were 4.8 mm (anterior) and 3.5 mm (posterior) which received a mean 88 Gy and 83.4 Gy respectively.

RESULTS

Only one patient (4%) plaqued for an anterior uveal melanoma developed secondary retinopathy (cystoid macular oedema). In contrast, 24 (52%) of the posterior choroidal melanoma patients developed retinopathy (p value <0.0001). Cataract developed in 18 (86%) eyes with phakic anterior tumour compared with seven (17%) eyes with posterior tumours (p value <0.0000). No posterior nasal tumours lost more than two lines of vision though 45% developed retinopathy.

CONCLUSION

While plaque radiation of anterior melanomas is more likely to cause reversible vision loss secondary to cataract, treatment of posterior tumours is more likely to be associated with irreversible loss because of retinopathy. Nasal location is also protective against severe loss of vision.

Enucleation

The three most common indications for enucleation are intraocular malignancy, trauma, and a blind, painful eye. Recommending enucleation is one of the most difficult therapeutic decisions in ophthalmology. In some cases of malignancy, cryotherapy, laser photocoagulation, diathermy, chemotherapy, and radiation therapy may be viable alternatives to surgery. When surgery is chosen, evisceration or exenteration may be alternatives to enucleation. Once the decision is made to perform enucleation or evisceration, the surgeon must choose from several types of implants and wrapping materials. These devices can be synthetic, autologous, or eye-banked tissues. With certain implants, the surgeon must decide when and if to drill for subsequent peg placement. In this review, the authors discuss choices, techniques, complications, and patient consent and follow-up before, during, and after enucleation. Controversies and results of the Controlled Ocular Melanoma Study are summarized.

Permanent 125iodine implants for recurrent malignant gliomas

PURPOSE

To determine the efficacy and toxicity of permanent 125iodine implants for recurrent malignant gliomas.

METHODS AND MATERIALS

Between January 1989 and January:, 59 patients with histologically confirmed recurrent malignant gliomas (22 nonglioblastoma malignant gliomas, 37 glioblastoma multiforme at the time of implant) received a permanent 125iodine implant. Patients ranged in age from 13-74 years. The median ages for the overall group, nonglioblastoma (nonGBM), and glioblastoma (GBM) groups was 47 years, 39 years, and 53 years, respectively.

RESULTS

With a median follow-up of 40 months, the median survival for the 59 total patients is 1.34 years; nonGBM 2.04 years, GBM 0.9 years. Factors predictive for poor prognosis were GBM histology, age 60 years or more, target volume 17 cc or more, and/or tumor location within the corpus callosum or thalamus. Reoperations have been performed in 24 (40%) patients; 15 (25%) for tumor progression; 3 (5%) for radiation necrosis; 2 (3%) for skull necrosis/infection, and 4 (7%) for other reasons (Ommaya reservoir insertion, catheter removal, hematoma evacuation).

CONCLUSION

Permanent 125iodine implants in selected patients with recurrent malignant gliomas are associated with reasonable long-term survival and a low risk of complications. Given the low incidence of radiation necrosis, future plans are to increase dose rate and/or total dose delivered with the permanent implant.

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.

Ophthalmic plaque radiotherapy for age-related macular degeneration associated with subretinal neovascularization

PURPOSE

To evaluate ophthalmic plaque radiotherapy for the treatment of subretinal neovascularization associated with age-related macular degeneration.

METHODS

In a prospective phase I clinical trial, we treated 23 patients (23 eyes) with ophthalmic plaque radiotherapy for subfoveal exudative macular degeneration. Palladium 103 ophthalmic plaque brachytherapy was delivered to a retinal apex dose of 1,250 to 2,362 cGy (rad). 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

Patients were followed up for a mean (+/-SD) of 19 +/- 10.7 months (range, 3 to 37 months). Six months after radiation therapy, three (16%) of 19 eyes had lost 3 or more lines of best-corrected visual acuity; 12 months after radiation therapy, four eyes (31% of 13 eyes), and 24 months after radiation therapy, only two (22% of nine eyes) lost 3 or more lines of visual acuity. No eye suffered sudden irreversible loss of central vision. No radiation retinopathy, optic neuropathy, or cataract could be attributed to radiotherapy within this follow-up period.

CONCLUSION

Ophthalmic plaque radiotherapy can be used to treat neovascular age-related macular degeneration. In contrast to external beam radiotherapy, ophthalmic plaque radiotherapy is a unilateral treatment, which allows a larger dose to be delivered to the macula with less irradiation of normal ocular structures. We have found no sight-limiting complications at the doses, dose rates, and follow-up evaluated in this study.

Seed localization in eye plaque brachytherapy

We describe a simple method for localizing seeds in eye plaques used for brachytherapy treatment of intraocular tumors and age-related macular degeneration. The method is based on obtaining magnified photocopy images of plaques with seeds in place and then using simple geometrical considerations to reconstruct seed coordinates with about 2% accuracy. A spreadsheet program is used for reconstruction and dosimetric calculations.

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.

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.

Feasibility study of the treatment of primary unresectable carcinoma of the pancreas with 103Pd brachytherapy

PURPOSE

The purpose of this study was to assess the feasibility of 103Pd brachytherapy in the management of primary unresectable carcinoma of the pancreas.

METHODS AND MATERIALS

Between August 1988 and January 1992, 11 patients with biopsy-proven primary unresectable adenocarcinoma of the pancreas were treated with 103Pd brachytherapy during laparotomy. The median age was 66 (range 57-70). The most common presenting symptoms were weight loss (eight patients), pain (six patients), and nausea/vomiting (four patients). Less common symptoms were jaundice (two patients), early satiety (two patients), and ascites (one patient). All patients underwent laparotomy and surgical staging. Eight patients had T3N0M0 disease, two patients had T3N1M0 disease, and one patient had T3N1M1 disease. The surgical procedure performed was biliary bypass in six patients, biopsy only in four patients, and gastric bypass in one patient. The average tumor dimension was 4.0 cm. The median activity, matched peripheral dose (MPD) and implanted volumes were 95.3 mCi, 124.4 Gy, and 33 cm3, respectively. The median initial dose rate was 0.21 Gy per hour. Five patients received postoperative external beam radiation therapy (median 45 Gy) and seven patients received chemotherapy postoperatively. The median follow-up was 7 months (range 1-19).

RESULTS

The median survival for the entire group of patients was 6.9 months. Ten of 11 patients have died, with 1 patient presently alive and receiving chemotherapy for metastatic disease to the liver, but without local progression radiographically. Five of 11 patients (45%) were locally controlled, defined as either a complete response or freedom from progression at the site of the implant as evaluated by computed tomography scan. In the other six patients, the median time to local progression was 6.9 months. Five patients developed distant metastases (four liver, one subcutaneous nodule). Two patients failed in regional sites (one omentum, one paraaortic lymph node). Four of 11 patients (36%) developed acute postoperative complications that included one gastric outlet obstruction, one duodenal perforation, and two with sepsis. One of 11 patients (9%) developed a late complication of radiation enteritis 5 months after implantation. The median survival for patients experiencing complications was 1.7 months as compared to 8.4 months for the patients who did not develop a complication (p = 0.10). Pain relief was obtained in five out of six (83%) of the patients presenting with pain for a median duration of 24 weeks. Local control did not appear to be related to the MPD, dose rate, implanted volume, treatment with external beam irradiation, or the use of chemotherapy. Patients were more likely to develop a complication if the MPD was greater than 115 Gy (four out of six patients) as compared to those whose MPD was less than 115 Gy (one out of five patients) (p = 0.12).

CONCLUSIONS

Because there was no improvement in median survival over conventional modalities, and the complication rate was high; we do not recommend 103Pd brachytherapy as a component of the treatment of unresectable adenocarcinoma of the pancreas.

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.