Proton Beam Therapy (PBT)
An overview of what to expect with proton beam therapy (PBT) for uveal melanoma—from diagnosis and treatment planning to the therapy process and follow-up care. It’s designed to help patients and families feel informed and prepared at each step of the journey.
1
Pre-Treatment Phase
Initial Diagnosis and Planning
- Diagnosis: Uveal melanoma is confirmed using imaging (ultrasound, OCT, MRI) and fundus photography.
- Referral: You’ll be referred to a specialized ocular oncology center equipped with a proton therapy unit.
Treatment Planning
- Eye Mapping and Tantalum Marker Placement:
- A short outpatient surgery is performed to attach tiny tantalum markers (radio-opaque clips) to the sclera around the tumor. These help precisely guide the proton beam.
- The eye needs to heal for about 1–2 weeks before the next step.
- CT or MRI Simulation:
- After healing, a CT scan is done to map your eye anatomy using the markers.
- A custom head mask or fixation device may be created to keep your head perfectly still during treatments.
2
During Treatment
Proton Beam Sessions
- Schedule: Typically 4 to 5 consecutive daily sessions, each lasting 20–30 minutes.
- Procedure:
- You’ll lie in a special treatment chair.
- A light beam is used to align your eye using the markers.
- Your eye must remain extremely still; sometimes, a device is used to gently hold the eyelids open or to help you focus on a target.
- The actual proton delivery takes only a few minutes.
How Proton Therapy Works
Proton beams are highly targeted, delivering most of their energy directly into the tumor (Bragg peak), minimizing damage to surrounding tissues like the optic nerve and retina.
3
After Treatment
Recovery and Monitoring
- No surgery needed after proton therapy sessions are complete—there’s no plaque to remove.
- Follow-Up Visits:
- Frequent follow-ups for the first year, often every 3 months.
Imaging and visual acuity tests are used to monitor tumor shrinkage and detect complications.
5
Lifestyle and Emotional Support
- Work and Activity: Many patients return to light activities during treatment.
- Emotional Well-Being: A cancer diagnosis and eye treatment can be emotionally taxing. Psychological support and patient advocacy groups (like A Cure In Sight) offer crucial help.
4
Possible Side Effects and Risks
Short-Term Side Effects
- Eye redness, irritation, or dryness.
- Mild fatigue.
- Vision may temporarily blur due to inflammation.
Long-Term Risks
- Radiation Retinopathy or Optic Neuropathy: Damage to retinal blood vessels or optic nerve.
- Vision Loss: Depends on tumor location—macula or optic nerve involvement increases risk.
- Cataracts: May form if the lens is within the radiation field.
- Secondary Glaucoma: Can develop due to radiation effects.
Tumor Response
- Tumor doesn’t disappear immediately—it shrinks slowly over months or even years.
Your eye may appear unchanged for a while, even though the tumor is no longer growing.