Photodynamic therapy (PDT) is a type of treatment that uses light along with chemicals known as photosensitizers to treat cancer and other conditions.
Photosensitizers can kill nearby cells when they come into contact with certain wavelengths of light. This is because the light causes the photosensitizer to create an oxygen that’s toxic to cancer cells or other cells being targeted. This process of killing cells by using both light and medication to create oxygen that’s poisonous to cells is called phototoxicity.
PDT is sometimes called photochemotherapy because of its use in cancer treatment. It’s also used to treat many different conditions, including acne and skin growths like warts. This is because of how potent the chemicals can be in destroying the cells or glands that cause these conditions.
PDT is used to treat a variety of cancer types.
Skin cancer is the most common type of cancer typically treated using PDT techniques. This is because the skin can easily be exposed to light. In this type of PDT, a photosensitizer is applied to your skin around the cancerous area and then exposed to a certain light wavelengths. This can then kill cancer cells or skin growths.
PDT needs light to work. At most, the light wavelengths used in PDT can only be used to get through about 1/3 of an inch (about 0.85 centimeters) of skin or other tissue. It can’t treat many cancers deep inside your body or those that have grown beyond the area they originally appeared.
PDT can be used to treat some cancers inside your body, though. These include:
- small-cell lung cancer
- esophageal cancer
- lesions in your esophagus that may become cancerous
- some bladder cancers
PDT can also be used to treat some non-cancerous conditions, such as:
- urinary tract infections caused by Escherichia coli (E. coli) bacteria
- periodontal diseases of your gums and mouth tissues
- both acute and chronic sinusitis (inflammation of the sinuses)
- gastritis, the inflammation of the stomach lining
- infections of the cornea (the clear layer of your eye in front of your pupil and iris)
PDT is usually performed as an outpatient procedure. This means that you can get the procedure done without having to be admitted into a hospital or stay in the doctor’s office after treatment for too long. This also means that you’ll stay awake during each part of the procedure. Your doctor won’t normally use any anesthesia unless the area being treated is inside your body.
PDT is done in several steps:
- Your doctor or a specialist injects a photosensitizer agent into your blood. They may use a needle or an intravenous (IV) method to get the agent directly into your veins. Your doctor may use one of several types of chemicals as a photosensitizer agent depending on what you’re being treated for:
- Porfimer sodium: This is the most commonly used photosensitizer. Your doctor will shine red laser light on this chemical to help kill cancer cells. It’s most often used to treat cancer in your lungs or esophagus.
- Methyl ester of aminolevulinic acid (ALA): This photosensitizer is often used to treat cancer on your scalp or face. Your doctor will also use red laser light on this chemical.
- Aminolevulinic acid (ALA): This photosensitizer is also used to treat cancer on your scalp or face. Your doctor will use a blue light on this chemical.
- You’ll return to the doctor or specialist’s office after a certain amount of time (usually one to three days) known as the drug-to-light interval.
- Your doctor or specialist will then shine the appropriate light on the area where the agent was applied. They may need to use a tool to get light into your throat or lungs to kill cancer cells. This causes the chemical to make the toxic oxygen that kills the cancer cells. This step usually takes a few minutes to an hour.
Your doctor may ask you to return several days after the procedure to make sure there’s no leftover tissue to be removed.
The cost for PDT may differ based on your insurance coverage, how much of your body needs to be treated by PDT, and how many visits you need to make to your doctor’s office to treat your condition.
The typical cost for PDT can range anywhere from $100 up to $4,000 or more for a single treatment. A series of PDT treatments can cost more than $10,000 over the course of a few months or years.
Recovery from PDT is usually quick and may only have minor side effects. You may feel fully recovered in less than a day and experience no side effects at all. If your doctor used any tools to get light inside your body, you may also feel sore, itchy, or raw where the agent or the light was applied.
You may experience some side effects around the area the agent was applied from even a brief exposure to light. This is because of the photosensitizing agent being in your blood or on your skin and making you more sensitive to light than usual. Some of these side effects can include:
- redness or rash
Do the following to make sure you don’t experience any side effects from exposure to light:
- Don’t go into direct sunlight or even indoor light that’s very bright.
- Don’t go to places where the sun is reflected off the ground, such as beaches with light sand or areas covered in snow.
- Wear a hat to protect your face and neck.
- Wear sunglasses to protect your eyes.
- Cover the area that was treated with clothing or another material that can block the light.
You may experience an allergic reaction to a photosensitizer. If you’re allergic to peanuts, using methyl ester of ALA can cause a life-threatening reaction because it contains peanut and almond oils.
If you’re already sensitive to light, your doctor may suggest that you don’t undergo PDT. Having a weakened immune system due to an existing condition or a medication can also increase your risk of complications from PDT.
Let your doctor know about any allergies, sensitivities, or existing conditions before you undergo PDT. Complications can include permanent skin damage or harm to your body because of an allergic reaction or other condition that’s affected by the therapy.
PDT is an effective cancer treatment and has many other uses beyond treating cancer. It’s also usually cheaper and allows you to recover more quickly than traditional treatments like chemotherapy.
PDT may not be able to treat cancer on its own. Your doctor may recommend PDT as part of a long-term cancer treatment plan to keep your cancer under control and to get rid of tumors or growths that may cause your cancer to spread.