Photodynamic Therapy

What is photodynamic therapy (PDT)?

Photodynamic therapy (PDT) destroys harmful cells, including cancer cells, using a combination of light and drugs called photosensitizers. Treatment happens in two parts. First, you’ll receive a photosensitizing drug. Then, a healthcare provider will expose the diseased cells to light. Light activates the photosensitizer, creating a chemical reaction that destroys the harmful cells.

Photodynamic therapy can only treat areas of your body where light can reach. This makes it especially useful for treating some skin cancers and precancers. Sometimes, providers use PDT to destroy cells on the lining of organs that they can reach with a light source.

Healthcare providers use PDT to treat cancers and precancers like:

• Skin cancer, actinic keratosis and Bowen disease (most common)
• Barrett’s esophagus
• Bile duct cancer
• Bladder cancer
• Esophageal cancer
• Head and neck cancer
• Lung cancer
• Pancreatic cancer

Noncancerous conditions that PDT treats include skin conditions, like severe acne and photoaging. But research is ongoing to find ways that PDT can help treat many other conditions, too.

How should I prepare for this procedure?

Your healthcare provider will review your medical history to make sure you’re a candidate for PDT. They’ll ensure you don’t have a sensitivity to light that could cause issues.

For example, some people with a history of cold sores experience flare-ups after PDT. But your provider can give you medication beforehand to keep this from happening.

What happens during photodynamic therapy?

Here’s what to expect during PDT:

1. You’ll receive the photosensitizer. Depending on where the treatment area is, you may take a pill, get an IV or have a solution applied to your skin.
2. The abnormal cells absorb the photosensitizer. All of your cells absorb the photosensitizer. But the drugs stay longer in abnormal cells. It may take anywhere from a few minutes to a few days for your cells to absorb enough of the drug for effective treatment.
3. Your provider exposes the target area to light. They may use laser lights, LEDs or natural sunlight. If the treatment area is inside your body, your provider will use a thin, flexible tube to shine light on the cells.
4. The light activates the photosensitizer. Under the light, the photosensitizing agent reacts with oxygen inside the cells. This causes a chemical reaction that destroys unhealthy cells.

How long does PDT take?

Most PDT treatment sessions take anywhere from 15 to 90 minutes. Treatment time depends on the size of the targeted area.

How painful is photodynamic therapy?

The light exposure part of treatment may feel unpleasant. People describe skin sensations on a spectrum. Skin may feel from warm to burning, from stinging to stabbing. Many factors will shape your experience, including the type of photosensitizing agent and the light source.

Let your healthcare provider know if you’re uncomfortable. The sensation is a sign that the treatment is working, but you don’t have to grin and bear the pain. Fans, ice packs and medications are all potential options that can provide relief.

What are the potential benefits and risks of photodynamic therapy?

Photodynamic therapy offers many benefits. PDT may be curative for some precancers and early-stage cancers. In some cases, it helps people live longer and provide symptom relief. There’s minimal scarring, and there aren’t any long-term side effects when it’s administered properly.

Still, as with any medical procedure, there are downsides to PDT. PDT directed at an organ can cause symptoms unique to that body part. For example, PDT to your esophagus can cause temporary side effects like difficulty swallowing. PDT to your lungs can cause shortness of breath.

Photosensitizing agents also make you more sensitive to light, even after treatment. It takes a while for the medicine to leave your body. For skin treatments, potential side effects of PDT include:

• Itching, stinging or burning
• Skin discoloration
• Swelling in the treatment area
• Scales, crusts or blisters on your skin receiving treatment
• Skin infections (very rare)

What happens after this procedure?

Most people go home the day of PDT treatment. But you’ll likely need to take extra steps to protect your skin and help the treatment area heal. Although everyone’s situation is different, here’s a day-by-day breakdown of what recovery may be like:

• Day 1. The treatment area may become red (light skin tones) or discolored (dark skin tones).
• Day 2. The reddening or discoloration may get more intense.
• Day 3 to 7. You may develop blisters (rare) or have itchiness or peeling skin.
• A week or two. Your skin should begin returning to normal.

Your provider will let you know if you need repeat PDT treatment sessions. For skin conditions, PDT results are usually semi-permanent, lasting several months. Whether you need repeat sessions depends on several factors, including the condition you have and how well you respond to treatment.

What is the recovery time?

It usually takes about two to six weeks to fully heal after PDT, depending on the area of your body that’s being treated. But you should start experiencing relief from side effects much sooner.

What can I do to make recovery go better?

You may need to make some adjustments for a while to protect yourself from light after PDT to your skin. Changes may include:

• Staying indoors (especially for the first 48 hours following treatment)
• Avoiding direct, bright or strong indoor lights
• Wearing sun-protective clothing and hats to avoid natural sunlight
• Staying away from environments where light may be reflected, like beaches
• Not using helmet-type hair dryers
• Not using strong reading or examination lamps

When should I call my healthcare provider?

Contact your healthcare provider if you’re experiencing severe discomfort during recovery. They may recommend home remedies or over-the-counter treatments that can help. Or you may need a prescription.