Photodynamic Therapy

Medically Reviewed by Brunilda Nazario, MD on July 02, 2020
4 min read

Photodynamic therapy (PDT) is a medical treatment that uses a combination of special drugs and light to destroy cancer cells and treat certain other problems. Drugs called “photosensitizing agents” become toxic when exposed to high-intensity light. Doctors expose them to the light and then direct them at cancer cells to kill a tumor. PDT may also break up the blood vessels that nourish cancer cells and “wake up” your immune system to help to fight the cancer.

This treatment works well and has few long-term side effects. Still, it's fairly new and isn't widely offered.

Your doctor may want you to have PDT if you have:

  • Basal cell cancer

  • Bowen's disease -- an early form of squamous cell carcinoma

  • Actinic keratosis (solar keratosis) – a rough, scaly patches of skin, usually found in older adults

  • Esophageal cancer

  • Non-small-cell lung cancer

  • Acne

  • Age-related macular degeneration

PDT can be an alternative to surgery or radiation for several kinds of cancer.  It may also be combined with other treatments. PDT has been shown to work just as well as surgery or radiation. It often costs less than other cancer treatments and doesn't appear to have long-term side effects.

Photodynamic therapy for skin cancer

First, your doctor may need to remove any crust or scale from the area of your skin that needs to be treated. A special cream with photosensitizing agents will be applied and the area gently covered.

How long it takes for the drug to be fully absorbed by your skin cells depends on the type your doctor uses. Some only take a few hours. Others may need up to 18 hours. If you need to wait a very long time, your doctor will send you home and ask you to come back the next day.

During the next stage of this treatment, your doctor will focus a special blue or red light onto the area of your cancer for about 15 minutes. You may feel stinging or burning while this is done. To make you more comfortable, your doctor may prescribe a pain medication to take ahead of time. You'll also be given goggles to wear to protect your eyes.

Photodynamic therapy for other cancers

For tumors inside your body, the photosensitizing drug is injected into your bloodstream. It takes a couple of days for the cancer cells to absorb it. Then your doctor will use a thin tube called an endoscope to send special light into your lungs or esophagus. 

PDT isn't right for everyone. For instance, people with certain blood diseases shouldn't have it. It's also not safe if you have an allergy to peanuts or almonds. Oils from these are used to make the creams that are used in PDT.

The lights used in PDT can only reach about a centimeter deep into your tissue. So the treatment won’t work on very large cancers, or tumors deep under your skin or inside your organs. It also doesn’t help if your cancer has spread to other parts of your body.

PDT is an outpatient treatment. This means that you won't have to spend the night in a hospital.

As with any cancer treatment, you may have side effects. What these are will vary from person to person. Some common ones include:

  • Photosensitivity (Your eyes and skin are bothered by light)

  • Burning

  • Stinging

  • Redness

  • Itching

  • Swelling

If your treatment was to your lungs or esophagus, you might have a cough and trouble swallowing or breathing. Let your doctor know if you have side effects so they can help you manage them. Many times, photosensitivity goes away on its own about 4-6 days after treatment.

Your skin will be very red and sore for a few days, like after a sunburn. Avoid putting anything on it for at least 48 hours. This includes aloe vera, vitamin C and most makeups and moisturizers.

PTD also makes your skin intensely sensitive to light. Because of this, your doctor will advise you to stay indoors as much as you can for the first few days after your treatment. You'll even need to avoid bright indoor light.

Make sure to cover up with protective clothing, glasses and sunscreen when you do go outside. Avoid light-colored concrete, snow or any other surface where light may be reflected onto your skin.

It's common for any skin that was treated with PDT to blister, scale, or crust before it heals. In about 3 weeks, any scab that's formed should fall off on its own. If there is any scarring, it’s usually small. Make sure to follow up with your doctor. In some cases, you may need more than one PDT session to make sure all the cancer is gone.