What is Photodynamic Therapy? Purpose, Procedure & Results

Photodynamic therapy (PDT) is a medical treatment that uses special light-activated drugs to destroy abnormal cells like cancer cells or treat certain skin conditions. Think of it as a targeted approach where medicine and light work together to treat specific areas of your body without affecting healthy tissue around it.

This gentle yet effective treatment has been helping people for decades. It's particularly useful for certain types of cancer, skin conditions, and eye problems. The beauty of PDT lies in its precision - it can target problem areas while leaving your healthy cells largely untouched.

What is photodynamic therapy?

Photodynamic therapy combines three key elements: a photosensitizing drug, oxygen in your tissues, and specific wavelengths of light. The photosensitizing drug is a special medication that becomes active only when exposed to particular types of light.

Here's how it works in simple terms: First, you receive the photosensitizing drug either through injection, topical application, or sometimes by mouth. This drug travels through your body and collects more heavily in abnormal cells than in healthy ones. After a waiting period, your doctor shines a specific type of light on the treatment area.

When the light hits the drug, it creates a form of oxygen that destroys the targeted cells. This process is called a photochemical reaction. The damaged cells then die off naturally, and your body clears them away over time.

Why is photodynamic therapy done?

PDT serves multiple medical purposes, and your doctor might recommend it for several different conditions. It's particularly effective for treating certain cancers, especially those on or near the surface of your body where light can easily reach.

The most common reasons doctors use PDT include treating certain types of skin cancer, lung cancer, esophageal cancer, and bladder cancer. It's also helpful for precancerous conditions like actinic keratosis, which are rough patches on your skin that could potentially become cancerous.

Beyond cancer treatment, PDT can address various skin conditions. These include certain types of acne, sun damage, and even some infections. Your doctor might also use it for age-related macular degeneration, a condition that affects your vision.

One of the biggest advantages of PDT is that it can be repeated multiple times in the same area if needed. Unlike some other treatments, it doesn't damage your healthy tissue significantly, making it a gentler option for many people.

What is the procedure for photodynamic therapy?

The PDT procedure typically happens in two main phases, and the exact process depends on what condition you're treating. Your doctor will walk you through each step, but here's what you can generally expect.

During the first phase, you'll receive the photosensitizing drug. For skin conditions, this might be a cream or gel applied directly to the affected area. For internal conditions, you might receive the drug through an IV or take it as a pill. The drug needs time to accumulate in the target cells.

The waiting period between drug administration and light treatment varies depending on the specific medication used. For topical applications, this might be just a few hours. For systemic drugs given through IV, you might wait 24 to 72 hours.

During the second phase, your doctor applies the specific light to the treatment area. For skin treatments, this involves placing you under a special light panel or using a handheld device. For internal treatments, your doctor might use a thin, flexible tube with a light at the end.

The light exposure usually lasts between 15 to 45 minutes, depending on the size and location of the treatment area. You might feel some warmth or tingling during this time, but the process is generally comfortable.

How to prepare for your photodynamic therapy?

Preparing for PDT is generally straightforward, but there are some important steps to follow. Your doctor will give you specific instructions based on your individual situation and the type of PDT you're receiving.

The most crucial preparation involves protecting yourself from light exposure. After receiving the photosensitizing drug, your skin and eyes will be more sensitive to light than usual. This sensitivity can last from a few days to several weeks, depending on the medication used.

Here are the key preparation steps you'll need to follow:

• Avoid direct sunlight and bright indoor lights for the specified period
• Wear protective clothing, including long sleeves, pants, and wide-brimmed hats when outdoors
• Use sunglasses and consider tinted car windows if you need to travel
• Remove any makeup, lotions, or perfumes from the treatment area
• Inform your doctor about all medications you're taking, especially those that increase light sensitivity

Your doctor might also ask you to avoid certain medications or supplements that could interfere with the treatment. Always follow these instructions carefully to ensure the best possible outcome.

How to read your photodynamic therapy results?

Understanding your PDT results involves looking at both immediate and long-term changes in the treated area. Your doctor will monitor your progress through regular follow-up appointments and sometimes additional tests.

In the first few days after treatment, you'll likely notice some changes in the treated area. For skin treatments, you might see redness, swelling, or mild peeling. This is actually a good sign - it means the treatment is working to clear away the abnormal cells.

The complete results of PDT typically become visible over several weeks to months. Your doctor will evaluate the treatment's success by examining the treated area and comparing it to your condition before treatment. For cancer treatments, this might involve biopsies or imaging tests.

Success rates vary depending on the condition being treated and its severity. For many skin conditions and early-stage cancers, PDT can be highly effective. Your doctor will discuss what to expect based on your specific situation.

What are the risk factors for complications with photodynamic therapy?

While PDT is generally safe, certain factors can increase your risk of complications or affect how well the treatment works. Understanding these risk factors helps you and your doctor make the best treatment decisions.

Your skin type and color can influence how you respond to PDT. People with very fair skin might be more sensitive to the light treatment, while those with darker skin tones might need adjusted light doses for optimal results.

Several medical conditions can increase your risk of complications:

• Existing skin conditions like eczema or psoriasis in the treatment area
• Autoimmune disorders that affect healing
• Blood clotting disorders
• Liver or kidney problems that might affect drug processing
• Previous radiation therapy to the treatment area

Certain medications can also increase your light sensitivity or interfere with the treatment. These include some antibiotics, diuretics, and anti-inflammatory drugs. Always provide your doctor with a complete list of your medications.

What are the possible complications of photodynamic therapy?

Most people tolerate PDT well, but like any medical treatment, it can have side effects. The good news is that serious complications are rare, and most side effects are temporary and manageable.

The most common side effects relate to the light sensitivity that comes with the photosensitizing drug. During the period when you're sensitive to light, accidental exposure to bright light can cause sunburn-like reactions, even from indoor lighting or brief sun exposure.

Local reactions at the treatment site are also common and usually expected. These might include:

• Redness and swelling that can last several days
• Mild to moderate pain or burning sensation
• Crusting or peeling of the skin
• Temporary darkening or lightening of the treated area
• Minor bleeding or oozing in some cases

More serious but rare complications can include severe skin reactions, scarring, or changes in skin pigmentation that don't fade over time. Some people might experience allergic reactions to the photosensitizing drug itself.

For treatments involving internal organs, there might be specific risks related to the treatment location. Your doctor will discuss these potential complications with you before treatment.

When should I see a doctor for photodynamic therapy concerns?

While most PDT side effects are normal and expected, there are certain situations where you should contact your doctor promptly. Knowing when to seek help ensures you get the support you need during your recovery.

You should contact your doctor immediately if you experience severe pain that doesn't improve with prescribed pain medication. Similarly, if you notice signs of infection like increasing redness, warmth, pus, or red streaking from the treatment area, this needs prompt medical attention.

Other concerning symptoms that warrant immediate medical contact include:

• Severe swelling that interferes with normal activities
• Blistering or severe skin breakdown
• Signs of allergic reaction like difficulty breathing, widespread rash, or swelling of face and throat
• Fever or chills that develop after treatment
• Unexpected bleeding that doesn't stop with gentle pressure

Even if you're not sure whether your symptoms are normal, it's always better to check with your healthcare team. They can provide reassurance or address any issues early before they become more serious.