What is photodynamic therapy (PDT)?
Photodynamic therapy (PDT) destroys harmful cells, including cancer cells, using specialized drugs called photosensitizers or photosensitizing agents. Light activates these drugs and creates a chemical reaction that destroys the harmful cells.
Doctors use PDT to treat a variety of medical conditions, including:
- Skin cancer and psoriasis (an itchy skin condition)
- Esophageal cancer, including Barrett’s esophagus, where cells at the base of the esophagus are damaged
- Non-small cell lung cancer
- Precancerous growths
- Warts caused by viruses
During treatment, providers apply photosensitizer medication directly to your skin or inject them into your bloodstream. The photosensitizing drugs concentrate in cancer cells and other unhealthy cells to make those cells more sensitive to light.
After applying the photosensitizer, your doctor shines a special light on the area undergoing treatment. Depending on the type of photosensitizer used, your doctor may use low-power red laser light, blue light or natural sunlight. Under the light, the photosensitizing agent reacts with oxygen, causing a chemical reaction that destroys unhealthy cells.
What should I expect from photodynamic therapy (PDT)?
Your doctor prescribes the photosensitizing agent that will be most effective, depending on your diagnosis. Your doctor applies topical medications directly to the skin receiving treatment. For some medical conditions, like esophageal cancer, your doctor administers photosensitizers intravenously (through an IV).
All the cells in your body absorb the photosensitizing agent, but these drugs stay longer in abnormal cells than in healthy cells. Some photosensitizing agents start collecting in unhealthy cells immediately. Others take hours or days to build up in large enough amounts for effective treatment. Your treatment timeline, including how many treatments you receive and how often you receive them, depends on the photosensitizing agent your doctor prescribes.
Outpatient PDT for skin conditions
Most PDT treatments occur as outpatient procedures in your doctor’s office. During the procedure:
- You put on protective gear or clothing, like protective eyewear, gloves or long pants, to help protect healthy skin and underlying tissues.
- You sit or lie on an examination table, exposing the area of skin to be treated.
- Your doctor applies light to your skin for a predetermined amount of time. The treatment length depends on the photosensitizing agent. In most cases, treatment takes 5 to 45 minutes.
PDT for esophageal cancer and lung cancer
Doctors perform phototherapy in a hospital or outpatient surgery setting for esophageal cancer and non-small cell lung cancers. Your doctor shines light onto the interior of your esophagus or lungs using thin, flexible tubes, called endoscopes or bronchoscopes, with light sources attached to them. You may go home the same day or stay overnight for observation.
You may receive repeat phototherapy treatments as needed. Your doctor determines if and when you receive further PDT.
Risks / Benefits
What are the benefits of photodynamic therapy (PDT)?
PDT offers many benefits compared to other medical treatments, including:
- No known long-term side effects when administered properly
- Usually performed as an outpatient procedure over a short time
- Can be repeated if necessary
- Less invasive and more precise compared to other treatments like surgery
- Often costs less than other treatments
What are the risks of photodynamic therapy (PDT)?
Like any medical procedure, PDT carries the risk of side effects. Photosensitizing agents affect both unhealthy and healthy cells, making you more sensitive to light even after your treatment is complete. Your skin and eyes may be more sensitive to light for as long as three months after your procedure.
Other possible side effects of PDT include:
- Swelling at or near the area of skin treated
- Discoloration of the skin
- Scales, crusts or blisters on the skin receiving treatment
- Itching, stinging or burning
- Skin infections
If you have PDT to your esophagus, your side effects may include:
- Difficulty swallowing
- Nausea and vomiting
- Narrowing or scarring of your esophagus
- Fluid buildup around your lungs
Risks of PDT for people living with non-small cell lung cancer include:
Recovery and Outlook
What is the prognosis (outlook) for people receiving photodynamic therapy (PDT)?
Most people return to their daily activities immediately following PDT. Some people need to take extra steps to protect skin and help the treatment area heal.
Your doctor may recommend covering the treatment area to help protect the skin. You may need to make lifestyle changes for short periods of time, depending on the photosensitizer your doctor uses. These lifestyle changes may include:
- Staying indoors
- Avoiding direct, bright or strong indoor lights
- Wearing 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 to Call the Doctor
When should I call the doctor concerning photodynamic therapy (PDT)?
If you are diagnosed with skin cancer or another medical condition that may benefit from PDT, ask your doctor if this treatment option may be a good choice for you.
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