Plaque Radiotherapy

• Plaque radiotherapy is a targeted internal radiation therapy for specific cancers, notably ocular tumors.
• It involves surgically implanting a small, radioactive disc (plaque) directly over the tumor.
• The plaque emits localized radiation, effectively destroying cancer cells over several days.
• Common side effects include temporary vision changes, dry eye, and irritation, with potential for long-term complications like cataracts.
• This treatment aims to preserve organ function, especially vision, while eradicating the tumor.

What is Plaque Radiotherapy?

Plaque radiotherapy is a precise and localized form of radiation therapy where a small, custom-designed radioactive disc, or “plaque,” is surgically placed directly onto or adjacent to a tumor. This method allows for a high dose of radiation to be delivered to the cancerous cells while sparing nearby healthy tissues from excessive exposure. It is most commonly employed in the treatment of intraocular melanomas, which are cancers originating in the eye, but can also be used for other specific tumor types.

The primary goal of a Plaque radiotherapy treatment is to eradicate the tumor while preserving the affected organ’s function, especially vision in the case of ocular cancers. The radioactive source within the plaque emits radiation over a predetermined period, targeting the tumor cells directly. This localized approach is crucial for sensitive areas like the eye, where extensive radiation could cause significant damage to vital structures.

How Plaque Radiotherapy Works

The mechanism of Plaque Radiotherapy involves several key steps, ensuring precise and effective tumor targeting. First, a tiny, concave plaque, typically made of gold, is custom-fabricated to match the shape and size of the tumor. Radioactive seeds, often containing Iodine-125 or Ruthenium-106, are then meticulously loaded into this plaque. These isotopes are chosen for their specific radiation properties, allowing for effective tumor cell destruction with minimal penetration beyond the target area.

The procedure begins with a surgical operation where the radioactive plaque is carefully sutured to the sclera (the white outer layer of the eye) directly over the tumor. The plaque remains in place for several days, typically between 2 to 7 days, depending on the type of isotope used, the tumor size, and the prescribed radiation dose. During this time, the plaque continuously emits radiation, delivering a concentrated dose to the tumor cells. Once the required dose has been delivered, a second, brief surgical procedure is performed to remove the plaque. The localized radiation damages the DNA of the cancer cells, preventing them from growing and dividing, ultimately leading to tumor regression.

Plaque Radiotherapy Side Effects

While Plaque Radiotherapy is highly effective and designed to minimize collateral damage, patients may experience various Plaque radiotherapy side effects, particularly affecting the treated eye. These side effects can vary in severity and duration, depending on the tumor’s location, size, and the total radiation dose delivered.

Common short-term side effects often include:

• Eye irritation and redness: The eye may appear red and feel irritated or gritty.
• Dry eye: Reduced tear production can lead to discomfort and blurred vision.
• Temporary vision changes: Blurry vision or a decrease in visual acuity may occur, often improving over time.
• Swelling of the eyelids: Mild to moderate swelling around the eye is common post-procedure.
• Pain or discomfort: Patients may experience mild pain, which can usually be managed with over-the-counter pain relievers.

Long-term side effects, though less common, can be more significant and may include:

• Cataracts: Clouding of the eye’s natural lens, potentially requiring surgical removal.
• Retinopathy: Damage to the retina, which can lead to permanent vision loss.
• Glaucoma: Increased pressure within the eye, potentially damaging the optic nerve.
• Optic neuropathy: Damage to the optic nerve, which can impair vision.
• Neovascularization: Growth of new, abnormal blood vessels in the eye.

Patients undergoing Plaque Radiotherapy are closely monitored by an oncology team, ophthalmologists, and radiation oncologists to manage these side effects and ensure the best possible outcome. Regular follow-up appointments are crucial for detecting and addressing any complications early.