Eye plaque brachytherapy versus enucleation for ocular melanoma: an analysis from the National Cancer Database

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.

Uveal melanoma incidence and survival analysis in Portugal between 2013 and 2022

PURPOSE

This study aims to provide a comprehensive overview of the clinical characteristics and epidemiology of uveal melanoma (UM) in the Portuguese population, evaluated at the National Reference Centre (NRC).

METHODS

A prospective observational study was conducted, involving patients consecutively diagnosed with UM at the Portuguese NRC between July 2013 and December 2022. The study collected data on demographic and tumour characteristics, clinical staging according to the American Joint Committee on Cancer (AJCC), treatment approaches, local disease control, patient survival, and the occurrence of distant metastases.

RESULTS

The study included a total of 316 patients, 53.8% female. The mean age at diagnosis was 61.8±14.2 years, and 75.0% of patients presented with symptoms. The mean annual age-adjusted incidence of uveal melanoma in Portugal between 2014 and 2022 was 2.4 cases per million (95% confidence interval [CI]: 2.1-2.8). For choroidal/ciliary body tumours, the overall cumulative survival and distant metastases-free survival (DMFS) rates at 5 years were 84.9% (95% CI: 78.7-91.1) and 79.4% (95%CI: 72.8-86.0), respectively. Notably, higher AJCC stages at presentation, the need for enucleation, and increased tumour thickness were associated with lower DSS and DMFS rates.

CONCLUSION

This study represents the most extensive analysis of UM epidemiology within the Portuguese population. The findings underscore the importance of early diagnosis and treatment in UM, as lower AJCC stages and smaller tumour thickness at diagnosis correlate with improved DSS and DMFS.

Novel intraocular shielding device for eye plaque brachytherapy using magnetite nanoparticles: A proof-of-concept study using radiochromic film and Monte Carlo simulations

PURPOSE

Eye plaque brachytherapy is a mainstay treatment for uveal melanomas despite potential toxicities to normal tissues. This work proposes a nanoparticle ferrofluid as a novel intraocular shielding device. With a modified magnetic plaque, the shielding particles are drawn to the tumor surface, attenuating dose beyond the tumor while maintaining prescription dose to the target.

METHODS AND MATERIALS

Ferromagnetic nanoparticles suspended in a silicone polymer were synthesized to provide a high-density shielding medium. The ferrofluid's half-value layer (HVL) was quantified for 125I photons using radiochromic film and Monte Carlo methods. A magnetic COMS plaque was created and evaluated in its ability to attract ferrofluid over the tumor. Two ferrofluid shielding mediums were evaluated in their ability to attenuate dose at adjacent structures with in vitro measurements using radiochromic film, in addition to Monte Carlo studies.

RESULTS

The shielding medium's HVL measured approximately 1.3 mm for an 125I photon spectrum, using film and Monte Carlo methods. With 0.8 mL of shielding medium added to the vitreous humor, it proved to be effective at reducing dose to normal tissues of the eye. Monte Carlo-calculated dose reductions of 65%, 80%, and 78% at lateral distances 5, 10, and 18 mm from a tumor (5-mm apical height) in a modeled 20-mm COMS plaque.

CONCLUSIONS

The magnitude of dose reduction could reduce the likelihood of normal tissue side effects for plaque brachytherapy patients, including patients with normal tissues close to the plaque or tumor. Additional studies, safety considerations, and preclinical work must supplement these findings before use.

Treatment of Uveal Melanoma With Radioactive Iodine 125 Implant Compared With Proton Beam Radiotherapy

Objective

To review the current state of radiation therapy for uveal melanoma and compare particle radiation and brachytherapy.

Patients and Methods

The medical records of 156 patients treated for uveal melanoma between May 30, 2012, and March 16, 2020, were retrospectively reviewed. Treatments consisted of either radioactive iodine 125 implant (RAI) or fractionated proton radiation (proton beam therapy [PBT]). Baseline characteristics were compared using a Wilcoxon rank sum test or χ² test. Outcomes were compared using Cox proportional hazards regression models or logistic regression models.

Results

The median length of follow-up after treatment was 2.7 years (range, 0.5 to 9.0 years). Patients who underwent treatment with RAI were older (median age, 67 vs 59 years; P<.001) and had a lower tumor classification (American Joint Commission on Cancer; P=.001) compared with those who underwent PBT. There was no significant difference between RAI and PBT in the outcomes of liver metastases, death, enucleation, tearing, vision loss, retinal detachment, tumor thickness, conjunctivitis, optic neuropathy, iris neovascularization, or neovascular glaucoma (all P>.05). Patients who underwent RAI treatment had significantly higher risk of diplopia (P<.001), cataract progression (P<.001), and maculopathy (P=.03) compared with those who received PBT. Patients who underwent RAI were at higher risk of eyelash loss (P=.006) compared with the PBT group.

Conclusion

Treatment with PBT and RAI has similar efficacy; however, there are differences in the adverse outcomes associated with these 2 modalities.

Radiobiological evaluation of organs at risk for electronic high-dose-rate brachytherapy in uveal melanoma: a radiobiological modeling study

Purpose

The objective of this study was to examine feasibility of single- or hypo-fraction of high-dose-rate (HDR) electronic brachytherapy (eBT) in uveal melanoma treatment.

Material and methods

Biologically effective doses (BED) of organs at risk (OARs) were compared to those of iodine-125-based eye plaque low-dose-rate brachytherapy (¹²⁵I LDR-BT) with vitreous replacement (VR). Single- or hypo-fractionated equivalent physical doses (SFEDs or HFEDs) for tumor were calculated from tumor BED of ¹²⁵I LDR-BT using linear-quadratic (LQ) and universal survival curve (USC) models. BED OARs doses to retina opposite the implant, macula, optic disc, and lens were calculated and compared among SFED, HFED, and ¹²⁵I LDR-BT. Electronic BT of 50 kVp was considered assuming dose fall-off as clinically equivalent to ¹²⁵I LDR-BT. All OARs BEDs were analyzed with and without silicone oil VR.

Results

For a single-fraction incorporating VR, the median/interquartile range of LQ (USC)-based BED doses of the retina opposite the implant, macula, optic disc, and lens were 16%/1.2% (33%/4%), 35%/19.5% (64%/17.7%), 37%/19% (75%/17.8%), and 27%/7.9% (68%/23.2%) of those for ¹²⁵I LDR-BT, respectively. SFED tumor values were 29.8/0.2 Gy and 51.7/0.5 Gy when using LQ and USC models, respectively, which could be delivered within 1 hour. SFED can be delivered within 1 hour using a high-dose-rate eBT. Even four-fraction delivery of HFED without VR resulted in higher OARs doses in the macula, optic disc, and lens (135 ~ 159%) than when using ¹²⁵I LDR-BT technique. A maximum p-value of 0.005 was observed for these distributions.

Conclusions

The simulation of single-fraction eBT, including vitreous replacement, resulted in significantly reduced OARs doses (16 ~ 75%) of that achieved with ¹²⁵I LDR-BT.

Brachytherapy or enucleation in ring melanoma patients: which is better? Preliminary results of the authors' own experiences

Purpose

A retrospective evaluation of effectiveness of brachytherapy or enucleation in treatment of rare form of uveal melanoma: ring melanoma.

Material and methods

Analysis comprised 49 patients treated from 2000 to 2019 for ring melanoma involving ciliary body. In 15 patients, primary treatment consisted of brachytherapy (¹⁰⁶Ru or ¹²⁵I), whereas in 34 patients, eyeballs were enucleated. The evaluation concerned differences between analyzed groups relating to the clinical and histopathological features as well as overall survival, cancer-specific overall survival, and disease-free survival.

Results

No significant differences between the analyzed groups were found with regards to clinical and histopathological features, apart from intra-ocular pressure (increased in the enucleation group). Kaplan-Meier analysis did not reveal any significant differences between the group treated with enucleation and the group undergoing brachytherapy, both with regards to overall survival (p = 0.325) and cancer-specific overall survival (p = 0.477). A significant difference was observed in disease-free survival (p = 0.009), which was significantly shorter in the group undergoing brachytherapy. In the analysis of parameters of the applied brachytherapy, no significant differences between patients with and without local recurrence were found. Mean observation period was 350.8 weeks (range, 24-996 weeks, SD = 231.6). A local recurrence occurred in 11 (22.4%) patients, including 3 (6.1%) in enucleation and 8 (16.3%) after brachytherapy groups. Metastasis developed in 11 (22.4%) cases after a mean follow-up of 133 weeks (33.25 months), range 3-655 weeks.

Conclusions

Preliminary observations may suggest that brachytherapy in this rare form of uveal melanoma, such as ring melanoma involving the ciliary body, may be taken into consideration as a useful alternative to enucleation. However, the confirmation of such an approach requires a larger patients’ group to be gathered, and also a longer follow-up period. This is especially important in patients with a good baseline visual acuity in the affected eye, or when the neoplasm is present in the remaining eye with vision.