This analysis will evaluate the investigators' institution's specific experience using Ru-106 isotopes, cryotherapy, or transpupillary thermotherapy (TTT) to treat persistent or recurrent RB in patients who previously underwent systemic IVC or IAC. The investigators aim to detail the demographics, clinical indications, success rates-specifically local control and globe salvage-, predictive factors for success, and complications of each modality of treatment within a tertiary eye care setting in Egypt.
As the most prevalent pediatric eye malignancy, retinoblastoma (RB) represents roughly 11% of cancers identified during an infant's first year, with the vast majority (95%) being diagnosed by age five. While medical priorities in developed nations have transitioned from merely saving the eye to actively preserving vision, clinical reality differs elsewhere; over 90% of children with RB live in developing or underdeveloped regions, where the disease often remains undetected until it has reached advanced stages that jeopardize the eye. (RB) is managed through a diverse range of therapeutic strategies, including systemic chemotherapy (IVC), intra-arterial (IAC) and intravitreal (IViC) approaches, cryotherapy, laser-based treatments, plaque radiotherapy, and surgical enucleation. Each of these methods presents a unique profile of clinical advantages and potential complications. Currently, systemic IVC is the most common frontline treatment, frequently used in tandem with consolidating focal therapies such as laser therapy, cryotherapy, or Plaque Brachytherapy. Plaque brachytherapy remains a vital tool for treating thicker tumors that are not suitable for laser or cryotherapy. It is particularly prioritized in salvage scenarios where preserving the eye is critical, such as when the patient's other eye has already been enucleated. A significant clinical benefit of plaque therapy is its localized nature; unlike external beam radiation therapy (EBRT), it does not elevate the risk of secondary malignancies in the patient. Whether utilized as an initial treatment or as a rescue measure following IVC or IAC, focal plaque radiotherapy has demonstrated eye salvage success rates between 55% and 79% for new or recurrent focal tumors. Ruthenium-106 (Ru-106) plaque radiotherapy has a long-standing history as both a primary intervention and a rescue therapy for tumors that fail to regress or recur after chemoreduction with a wide range of prescribed apex doses and treatment results. Research indicates that using isotopes like Ruthenium-106 and Iodine-125 results in impressive local tumor control (60%-90%) and high globe preservation rates. To the best of the investigators' knowledge, no previous research analysis has been done on the outcomes of consolidation therapy using Ru-106, laser, or cryotherapy for retinoblastoma in the Egyptian population.
Study Type
OBSERVATIONAL
Enrollment
150
The 810 nm red laser (Iridex Oculight SLx) is used via an indirect delivery system for transpupillary applications under general anesthesia. The goal is a gentle white spot at the tumor-retina boundary. Technique: Placement: Begin at the lesion edge, placing burns half-on and half-off the tumor. Titration: Increase power/duration until a reaction is seen. Punctate hemorrhage warns of maximum power density. Coverage: Create a perimeter with overlapping burns, then treat the entire lesion. Central thick areas may not whiten. Parameters: Set duration to 9000 milliseconds (ms) and interval to 50 ms for foot-pedal control (continuous mode). This allows for photocoagulation (1-10s) or thermotherapy (30-60s). Primary (Peripheral/Macular): Start at 300 milliwatt (mW). Chemoreduction (Large Tumors): Start at 400-500 mW; can increase to 800 mW with careful monitoring if no reaction occurs.
The ERBE Erbokryo AE system is utilized to treat peripheral lesions. Before use, the probe must be tested for proper ice ball formation. Technique: Localization: Position the probe tip using indirect ophthalmoscopy and scleral indentation. Freezing: Center the tip under the tumor. The ice ball must extend 1-2 mm beyond the tumor apex to encompass potential vitreous seeds. Monitoring: Control the lateral spread to minimize damage to healthy retina. Cycles: Apply double or triple freeze-thaw cycles for maximum efficacy. Precautions: Limit treatment to 2-3 sites per session to reduce the risk of secondary serous or rhegmatogenous retinal detachment.
Percentage of Globe salvage for treatment with Brachytherapy
The number of eyes that were not enucleated due to the success of brachytherapy in regressing the tumour in these eyes, compared to the total number of eyes that were treated with brachytherapy.
Time frame: Baseline
Percentage of Globe salvage for treatment with cryotherapy
The number of eyes that were not enucleated due to the success of cryotherapy in regressing the tumour in these eyes, compared to the total number of eyes that were treated with cryotherapy.
Time frame: Baseline
Percentage of Globe salvage for treatment with transpupillary thermotherapy
The number of eyes that were not enucleated due to the success of transpupillary thermotherapy in regressing the tumour in these eyes, compared to the total number of eyes that were treated with transpupillary thermotherapy.
Time frame: Baseline
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Plaque insertion is performed under general anesthesia. Precise tumor localization is achieved through simultaneous indirect ophthalmoscopy and transillumination; the tumor projection is marked on the sclera using blue ink. Muscles may be temporarily detached for proper seating. Planning and Dosimetry:Equipment: Ru-106 plaques (e.g., BEBIG) are used for tumors up to 7 mm thick and 17 mm in diameter.Dose: Following American Brachytherapy Society (ABS) guidelines, 90 gray (Gy) is delivered at 0.6-1.05 Gy/hr over 3-7 days.Margins: Calculation includes tumor height + 1 mm sclera. A 2-3 mm lateral margin and a 1 mm safety margin are maintained. Vitreous Seeds: Add 1 mm to the thickness calculation if local seeds are present.