Study Of Surgical Radiation Shielding With Vitrectomy And Silicone Oil Tamponade For The Protection Of Radiation Induced Ocular Injury
A prospective, experimental, case series of 20 patients, with choroidal melanoma, in which pars plana vitrectomy and Silicone oil as vitreous substitute will be used as intraocular shielding for attenuating the deleterious effects of radiation dose delivered to healthy ocular tissue during Iodine-125 plaque brachytherapy treatment and assess if the treatment can reduce the incidence and severity of radiation-induced adverse effects like radiation retinopathy and permanent loss of vision.
|Study Design:||Endpoint Classification: Safety/Efficacy Study
Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Prevention
|Official Title:||A Prospective Pilot Study of Surgical Radiation Shielding With Vitrectomy and Silicone Oil Tamponade for the Protection of Radiation-induced Ocular Injury in the Treatment of Choroidal Melanoma With Radioactive Iodine-125 Plaque Brachytherapy|
- Vision Loss [ Time Frame: 1 year ] [ Designated as safety issue: No ]The loss of 5 or more letters from the base line on an ETDRS chart after 1 and 2 years of follow-up.
- Severe Visual Loss [ Time Frame: 3 years ] [ Designated as safety issue: No ]The loss of 15 or more letters from base line on and ETDRS chart after three years of follow-up (No). Contrast sensitivity loss: the loss of 2 or more lines on a Pelli-Robson Chart after 1 and 2 years of follow-up.
|Study Start Date:||July 2011|
|Estimated Study Completion Date:||July 2014|
|Estimated Primary Completion Date:||July 2013 (Final data collection date for primary outcome measure)|
Experimental: 1000CsK Silicon Oil Tamponade
Patients whom meet all inclusion / exclusion criteria will be selected for I125 brachytherapy; however, prior to the surgical placement of the brachytherapy plaque, a pars plana vitrectomy will be performed and the eye will be filled with 1000CsK silicon oil. The silicon oil will remain inside the eye for the time that the brachytherapy plaque stays in place. During the surgery for plaque removal, the silicon oil will be extracted from the eye.
Other: 1000CsK Silicon Oil Tamponade
Details covered in arm description
Melanoma arising from the choroid and ciliary body is the most common primary intraocular cancer.1 The Collaborative Ocular Melanoma Study (COMS) randomized clinical trial of I-125 brachytherapy versus enucleation for medium-sized choroidal melanoma (2.5-10.0 mm in thickness and ≤ 16 mm in diameter) showed that, for patients who met the eligibility criteria, there was no statistically significant difference in all-cause mortality between I-125 brachytherapy and enucleation 5, 10, and 12 years following treatment.2-4 The COMS trial supported the use of globe-conserving I-125 brachytherapy. Following brachytherapy, however, visual acuity in the treated eye generally declined at a rate of approximately 2 lines of visual acuity per year and nearly 45% of patients lost ambulatory vision (≤20/200) in the treated eye by 3 years.5
Adverse effects of plaque brachytherapy include cataract, radiation-associated proliferative retinopathy, maculopathy and papillopathy. Radiation maculopathy, which may result in decreased central vision, cystoid macular edema (CME), macular ischemia, and chorioretinal atrophy, was reported in other series in 18% to 43% of treated eyes within 5 years after brachytherapy.6, 7 Typical onset occurred 18-24 months following treatment.6, 8 Primary risk factors for radiation papillopathy and maculopathy were total radiation dose to the affected structures, proximity of the tumor to the affected structures and systemic conditions such as diabetes mellitus.7, 9, 10 No treatment for radiation maculopathy or papillopathy has been proven to be effective in a randomized clinical trial.
Radiation injury to vital structures may be avoided or shielded with the use of materials such as lead that have a higher effective atomic number and density than tissue. However, solid metals are not amenable to use within the eye (Figure 1).11
There have been previous efforts to try to use a vitreous substitute in order to protect intraocular structures from the deleterious effects of radiations.12 In an animal study, Finger et al, demonstrated that iodinated contrast agents (iophendylate, iohexol, and iopamidol) could block radiation intraocularly. But these substances were highly toxic and could not be retained in the eye due to high water solubility.12
The technique of vitrectomy and oil tamponade during plaque brachytherapy has been performed previously in humans by Dr. Tara McCannel at UCLA. During a paper presentation at the 2010 meeting of the American Society of Retina Specialist in Vancouver, BC, the first series of 10 patients were presented, and no complications of the technique were reported. It is now a commonly applied technique at this center for treatment of choroidal melanoma (Oncology Times 2010; 32(14):36, UCLA, Clinical Update 2011; 20(1):1, 4)
In this prospective pilot study the investigators propose that patients will undergo standard plaque placement for treatment of their ocular melanoma in addition to pars plana vitrectomy and silicone oil infusion. When patients return for their scheduled plaque removal one week later, they will also undergo removal of the silicone oil from the eye. Placement of silicone oil should not alter the radiation dose delivered to the tumor, as there is no physical space between the tumor and the radioactive plaque for silicone oil to be present. The reduction in radiation to healthy ocular structures by using the oil technique may be sufficient to avoid the clinical complications caused by radiation-induced injury.
|United States, Colorado|
|University of Colorado Eye Center||Recruiting|
|Aurora, Colorado, United States, 80045|
|Contact: Mary Preston 720-848-2035 firstname.lastname@example.org|
|Principal Investigator:||Scott C Oliver, MD||University of Colorado, Denver|
|Principal Investigator:||Raul Velez-Montoya, MD||University of Colorado, Denver|