Photodynamic Therapy Procedure
Overview
Photodynamic therapy (PDT) uses a special drug called a photosensitizer and a specific type of light. The drug becomes active when exposed to light, creating a chemical reaction that destroys abnormal or damaged cells.
This process targets unhealthy tissue while causing minimal harm to surrounding healthy tissue. Doctors most often use PDT to treat certain types of cancers and skin conditions, including actinic keratosis, some forms of skin cancer, and severe acne.
It is also used for precancerous growths and sun-damaged skin. PDT works best for areas near the skin surface or lining internal parts, as the light used can only reach about 1 centimeter (about 1/3 inch) into tissue. It is not effective for deep tumors or widely spread cancers.
How Photodynamic Therapy Works
Photodynamic therapy involves two primary steps:
- A healthcare provider applies or injects a photosensitizer, which collects in abnormal or damaged cells.
- After a waiting period, the treated area is exposed to a specific wavelength of light, usually from a laser or LED, which activates the drug.
When activated, the drug produces a type of oxygen that destroys nearby unhealthy cells. This method selectively targets diseased cells and spares most healthy tissue. Most PDT treatments are performed in outpatient settings, and patients usually go home the same day. Recovery time is typically short.
Basic Steps in Photodynamic Therapy
| Step | Description |
|---|---|
| Photosensitizer | Applied or injected |
| Light Activation | Specific light used on targeted area |
| Cell Destruction | Damaged or cancerous cells are destroyed |
Many people consider PDT because it is a less invasive alternative to other treatments. Learning how it works helps patients make informed decisions and discuss care options with their doctors.
Types of Photodynamic Therapy
Photodynamic therapy can be delivered in two main forms, depending on the treatment area and depth:
Topical Photodynamic Therapy
Topical PDT uses a photosensitizing cream or gel applied directly to the skin. Doctors most often use it to treat surface-level skin problems, such as actinic keratosis, precancerous patches, or some nonmelanoma skin cancers.
After the cream is applied, it usually stays on the skin for a set amount of time, often a few hours. This lets the medicine absorb into abnormal cells. A special light is then shone on the treatment area to activate the medicine and destroy the targeted cells.
Topical PDT is noninvasive and usually done in a doctor’s office. Side effects are mostly mild, like redness, swelling, or a burning feeling, and these effects usually fade quickly. This type of PDT is not useful for deeper tumors since the medicine and light do not travel far below the skin surface.
Systemic Photodynamic Therapy
Systemic PDT involves giving the photosensitizing drug as a pill or through an IV. The drug travels throughout the body and collects in both normal and abnormal cells, but it stays longer in abnormal cells.
Doctors use this approach to treat cancer just under the skin or lining internal organs, such as the esophagus or lungs. After waiting for the medication to leave most normal cells, they use a laser or light probe to target the tumor.
Systemic PDT is more complex and usually requires monitoring in a clinic. People may need to avoid bright light for days or weeks because their skin and eyes can be extra sensitive after treatment. Unlike topical PDT, systemic therapy can access deeper areas, though the light still reaches only shallow depths.
Step-By-Step Photodynamic Therapy Procedure
Pre-Procedure Evaluation
Before starting PDT, a healthcare provider checks the patient’s medical history and current health. This includes any allergies, recent illnesses, and ongoing medications. The provider examines the area to be treated and discusses the patient’s goals and expectations.
The provider may take photographs or measurements to track changes during treatment. Patients receive instructions on how to care for their skin before the procedure, such as avoiding sun exposure, stopping certain medications, or not applying makeup or lotions on the treatment area.
| Step in Evaluation | Description |
|---|---|
| Medical history review | Check for risks or health issues |
| Skin exam | Identify treatment area |
| Instructions and preparation | Guidelines before the procedure |
Photosensitizer Administration
Once preparations are finished, the provider chooses and applies a photosensitizing agent. This drug makes the targeted cells sensitive to light. Depending on the condition, the drug can be applied directly to the skin, taken by mouth, or given by injection.
For skin procedures, a topical solution called aminolevulinic acid (ALA) or a similar agent is usually used. The provider spreads it evenly over the treatment area. The patient then waits for an incubation period, usually lasting from 30 minutes to 3 hours. During this time, abnormal or damaged cells absorb the drug. The provider may cover the area or advise the patient to avoid light until the next step.
Light Exposure Process
After the incubation, the provider exposes the treated area to a specific type of light. The choice of light—such as blue light, red light, or laser—depends on the drug used and the tissue being treated. The light activates the photosensitizer, which creates a reaction that destroys the damaged cells.
Exposure usually lasts from a few minutes to about 20 minutes. Providers may give protective eyewear. Patients might feel tingling, warmth, or mild discomfort during the process.
After the treatment, the provider may cool the skin with a fan or apply soothing creams. Patients should avoid sunlight or bright lights for one or two days after PDT, as their skin remains sensitive. Providers review specific aftercare steps to help reduce side effects and support healing.
Post-Treatment Care
After photodynamic therapy (PDT), the treated skin often appears red, swollen, and sensitive, much like a sunburn. These effects usually go away in a few days. To minimize discomfort, apply cool packs or ice wrapped in a soft cloth for about 20 minutes at a time. Avoid putting ice directly on the skin. Swelling is often most noticeable around the eyes and can be worse in the morning.
Protect the treated areas from sunlight and bright indoor lights for at least 48 hours after treatment. The skin is highly sensitive, and even brief sun exposure can cause more redness or irritation. Wear a wide-brimmed hat and use gentle clothing to cover the area if going outside is necessary.
Common Care Tips
- Use a gentle cleanser and avoid scrubbing the treated skin.
- Keep the skin moisturized with a recommended ointment or cream.
- Stay away from harsh products, makeup, or shaving the area until healing improves.
- Over-the-counter pain relievers can help with discomfort if needed.
Conditions Treated with Photodynamic Therapy
Photodynamic therapy (PDT) treats several medical conditions, mainly related to the skin and some types of cancer. It works best for surface-level problems where light can easily reach. Common conditions treated with PDT include:
- Skin cancers, such as basal cell carcinoma
- Actinic keratosis (precancerous, rough skin patches)
- Some types of lung and esophageal cancers
- Severe acne
- Sun-damaged skin
Doctors sometimes use PDT to manage other health issues, including certain viral, fungal, and bacterial infections, if standard treatments fail.
| Condition | Reason for Use |
|---|---|
| Skin cancer | Targets cancer cells |
| Actinic keratosis | Reduces precancer risk |
| Severe acne | Lowers bacteria, oil |
| Sun-damaged skin | Repairs skin damage |
| Lung/Esophageal cancers | Reaches tumors in airway |
Doctors can perform PDT in an office, often without needing a hospital stay. Some cancers require combining PDT with surgery, chemotherapy, or radiation therapy. PDT works best for small, well-defined areas and is not commonly used for cancers that have spread widely.
It may also help with some growths and early-stage tumors inside the body, if light can reach them. Doctors usually choose this treatment when other methods do not work well or to avoid more aggressive options.
Benefits and Effectiveness
Photodynamic therapy (PDT) uses light and special medicines to treat several health problems, including some cancers and skin conditions. PDT offers a less invasive alternative to surgery and usually allows patients to avoid a hospital stay.
PDT can target problem areas precisely, causing less harm to healthy tissue nearby. Most patients undergo the procedure as outpatients and can return home the same day. Key benefits of PDT include:
- Minimal long-term side effects when used correctly.
- Usually a quick procedure.
- Can be repeated if needed.
- May treat more than one area at a time.
- Has a faster recovery compared to surgery.
A table below shows PDT benefits compared to other common treatments:
| Treatment | Invasiveness | Recovery Time | Repeatable | Targeted Treatment |
|---|---|---|---|---|
| Photodynamic Therapy | Low | Short | Yes | Yes |
| Surgery | High | Long | Sometimes | Sometimes |
| Radiation Therapy | Medium | Variable | Sometimes | Sometimes |
PDT rarely causes long-term side effects. Studies show that PDT can match the effectiveness of surgery or radiation for certain types of cancers and pre-cancers. Dermatologists frequently use PDT to treat conditions like actinic keratosis, which are rough, scaly patches on the skin resulting from sun exposure. PDT can address several patches in one session.
Potential Risks and Side Effects
Photodynamic therapy (PDT) is usually safe, but patients can experience some side effects. These often depend on the area treated and the type of photosensitizing drug used. Most side effects are mild and short-term. Common side effects include:
- Redness
- Swelling
- Itching
- Burning or stinging at the treatment site
- Small blisters
These symptoms might last a few days up to a week. Sometimes, the treated skin may become scaly or crusty for several days. Less common risks:
- Allergy to the photosensitizing drug
- Scarring
- Change in skin color
- Sensitivity to sunlight lasting for several weeks
In rare cases, people may notice post-inflammatory redness that lasts longer. If the treated area is near sensitive tissues, temporary damage may occur to nearby healthy skin.
| Side Effect | Frequency | Duration |
|---|---|---|
| Redness and swelling | Common | Up to 1 week |
| Burning or stinging | Common | 24-48 hours |
| Small blisters | Sometimes | Few days |
| Scarring | Rare | May be permanent |
| Increased light sensitivity | Sometimes | Several weeks |
| Allergy to drug | Rare | Varies |
Patients should follow their doctor’s directions closely to reduce the chance of problems after treatment.
