What Is Photodynamic Therapy (PDT)?
Photodynamic Therapy (PDT) is a non-invasive treatment that utilizes a combination of a photosensitizing agent and blue light to target and eliminate abnormal or cancerous cells. The process begins with the application of a photosensitizing topical drug to the affected area. This agent remains inactive until exposed to a specific wavelength of light, typically blue light, which triggers a chemical reaction. This reaction generates reactive oxygen free radicals that selectively destroy unhealthy or cancerous cells, leaving the surrounding healthy tissue relatively unharmed.
Photodynamic therapy (PDT) is a versatile treatment option for a variety of skin conditions. It effectively targets precancerous lesions, such as actinic keratosis, as well as certain types of cancers, including non-melanoma skin cancers like basal cell carcinoma and squamous cell carcinoma. Beyond these conditions, PDT also addresses inflammatory issues such as acne.
One important aspect of PDT is post-treatment light sensitivity. After the procedure, the treated skin becomes highly sensitive to light, particularly sunlight, for a few days. For this reason, it’s generally recommended to undergo PDT in the cooler months, when patients can more easily avoid direct sun exposure and reduce the risk of complications like prolonged irritation or hyperpigmentation.
PhotoDynamic Therapy vs Daylight PhotoDynamic Therapy
Photodynamic Therapy (PDT) and Daylight Photodynamic Therapy both treat conditions like sun damage, actinic keratosis, and acne. However, their application methods differ. In traditional PDT, a photosensitizing agent is applied in the clinic, followed by controlled laser light exposure to activate the treatment. Daylight PDT, in contrast, involves applying the same agent, but instead of clinical light, patients are exposed to natural light to trigger the reaction.
What Conditions Can Photodynamic Therapy Treat?
Health Canada has approved photodynamic therapy (PDT) as an effective treatment for various skin conditions, including precancerous lesions, sun damaged skin and acne.
Photodynamic Therapy to Treat Precancerous Lesions and Sun-damaged Skin
Photodynamic Therapy (PDT) is a medically advanced treatment primarily used to address precancerous lesions, such as actinic keratosis, and certain forms of early-stage skin cancer. This procedure involves the application of a photosensitizing agent that selectively accumulates in abnormal, damaged, or precancerous cells. When activated by a specific light source, the agent triggers a reaction that targets harmful cells, such as cancer cells, while preserving the surrounding healthy cells.
PDT is particularly effective for patients with extensive sun damage, providing a non-invasive option for managing areas at high risk of developing skin cancer, while minimizing tissue damage and preserving the overall integrity of the skin.
Photodynamic Therapy for Acne
Photodynamic Therapy (PDT) is an effective treatment option for moderate to severe acne, particularly for inflammatory forms. It works by targeting overactive sebaceous glands that contribute to excess oil production and acne-causing bacteria. By applying a photosensitizing agent followed by controlled light exposure, PDT helps to shrink the oil glands, reduce inflammation, and eliminate the bacteria responsible for breakouts.
Patients typically require multiple sessions to achieve optimal results, with improvements seen over time. PDT offers a minimally invasive approach with little downtime, making it an appealing option for those looking to reduce acne and prevent future breakouts.
The Medical Procedure
Initial Consultation and Medical History
Before undergoing Photodynamic Therapy (PDT), a thorough initial consultation with your healthcare provider is conducted to discuss your treatment goals and expectations. During this consultation, your medical history is carefully reviewed by your healthcare provider to identify any potential concerns, such as allergies or sensitivities to the photosensitizing agents used in the procedure. It’s crucial to inform your healthcare provider about any history of skin conditions, especially cold sores, as these can affect the treatment process and outcomes. Understanding your medical background helps the specialist tailor the therapy to your specific needs while minimizing risks.
Preparation Before the Procedure
To ensure optimal results from your Photodynamic Therapy (PDT) session, certain preparations are necessary. Here are key recommendations for what to avoid prior to your treatment:
- Makeup: It is advisable to avoid wearing makeup on the treatment area on the day of your session. This helps prevent any interference with the absorption of the photosensitizing agent.
- Sunscreen: Refrain from using sunscreen on the area to be treated, as it may create a barrier that hinders the effectiveness of the photosensitizer.
- Topical Creams: Avoid applying any creams or lotions, particularly those containing retinoids or alpha-hydroxy acids (AHAs), for at least a few days before the procedure. These products can increase skin sensitivity and may interfere with the treatment.
- Excess Sun Exposure: Limit sun exposure in the days leading up to your PDT session. Sunburned or tanned skin may be more sensitive to light and could affect the treatment outcome.
Skin Cleansing and Lesion Preparation
Prior to the initiation of Photodynamic Therapy (PDT), proper skin cleansing and lesion preparation are essential for maximizing treatment efficacy. Your healthcare provider typically guides this process, which involves the following steps:
- Cleansing: The treatment area will be thoroughly cleansed to remove any dirt, oil, and residual products. This ensures that the photosensitizing agent can be absorbed effectively.
- Lesion Preparation: In some cases, your healthcare provider may carefully scrape or prepare the skin lesion to remove superficial layers of abnormal cells, including cancerous cells. This step helps enhance the penetration of the photosensitizer, making the treatment more effective.
These preparatory steps, overseen by your healthcare provider, are crucial in ensuring that the skin is ready for the application of the photosensitizing agent, facilitating optimal results in targeting abnormal cells during the PDT session.
Application of The Photosensitizing Agent
After thorough cleansing and preparation of the affected area, the photosensitizing agent is carefully applied. This process ensures that the agent adheres effectively to the skin, allowing it to accumulate in the targeted cells. Following application, there is a crucial waiting period of about 1.5 to 2 hours. During this time, the agent continues to absorb into the skin, enhancing its efficacy. This waiting period is vital as it allows the photosensitizer to maximize its interaction with the abnormal cells, setting the stage for effective light activation and subsequent destruction of these cells.
Blue Light Exposure
Blue light exposure is a critical component of Photodynamic Therapy (PDT), as it activates the previously applied photosensitizing agent through a photochemical reaction. When the skin is exposed to blue light, the emitted energy interacts with the photosensitizer, exciting its molecules. This excitation causes the photosensitizing agent to react with oxygen molecules, leading to the generation of reactive oxygen species (ROS). These ROS selectively target and destroy abnormal cells, such as precancerous lesions and acne-causing bacteria, while preserving the surrounding normal cells.
During the light exposure, which typically lasts around 15 to 30 minutes, patients may experience a mild sensation of warmth or tingling in the treatment area. This response is generally well-tolerated, and any discomfort is temporary.
What Is the Treatment Time for Photodynamic Therapy?
The treatment time for Photodynamic Therapy (PDT) can vary depending on the area being treated. Typically, the application and absorption of the photosensitizing agent takes around 1.5 to 2 hours. Afterward, light exposure lasts approximately 15 to 30 minutes. Overall, the entire treatment time usually ranges from 1.5 to 3 hours, covering both the preparation and treatment phases.
Is Photodynamic Therapy Painful?
During Photodynamic Therapy (PDT), patients often experience a mild to moderate stinging or tingling sensation at the treatment site. This discomfort generally decreases once the treatment is underway. After the procedure, some individuals may feel heightened sensitivity or a sensation similar to sunburn, but this typically resolves within a few days. For those concerned about pain, discussing pain management options with the specialist prior to the procedure is advisable to ensure a comfortable experience.
What Are the Drawbacks of Photodynamic Therapy?
The effects of photodynamic therapy (PDT) can vary depending on the individual and the area treated, but several common reactions are part of the healing process. Here’s what you might experience after your session:
- Redness and swelling: After the procedure, the treated area may become red and swollen. This is a normal reaction as the skin begins to heal and typically subsides within a few days.
- Mild to moderate discomfort: Patients often experience a stinging or burning sensation during and shortly after the treatment. This discomfort usually lessens over time and can be managed with pain relief options if necessary.
- Peeling and crusting: In the days following the treatment, the skin may peel or form small crusts, particularly in areas where abnormal cells were destroyed. This is part of the natural healing process and can last for about a week.
- Increased sensitivity to light: Treated skin becomes temporarily more sensitive to sunlight and bright indoor lights. It is crucial to avoid direct sun exposure for several days post-treatment and to use a broad-spectrum sunscreen to protect the skin.
How Long Does It Take To Recover From Photodynamic Therapy?
Recovery from Photodynamic Therapy generally unfolds over several weeks. In the first two to four days, redness, swelling, and peeling are expected as the skin begins to heal. During this initial phase, your skin will be highly sensitive to light and require extra care, including diligent sun protection. Most patients experience full skin recovery within two to four weeks, though this may vary based on the condition treated, skin type, and the intensity of the therapy. If your skin hasn’t fully healed after four weeks or new symptoms arise, it is important to consult your dermatologist for a follow-up assessment.
How Long Until I See Results From Photodynamic Therapy?
Visible improvements from Photodynamic Therapy can start to appear within a few days, particularly for conditions like acne and sun-damaged skin. You may notice reduced redness, smoother texture, and overall improvement in skin clarity. However, full results typically take between 4 to 12 weeks to develop, as the treatment continues to work on deeper skin layers. For precancerous lesions, healing usually occurs within this timeframe as well. The exact timing may vary depending on the condition being treated and individual skin response.
Post-Treatment Care Guidelines
After Photodynamic Therapy, careful post-treatment care is crucial to ensure proper healing and avoid complications:
- Avoid direct sunlight for at least 48-72 hours post-treatment. Stay indoors as much as possible, and when you do go outside, wear protective clothing and a wide-brimmed hat to shield the treated area from UV rays.
- Minimize exposure to bright indoor lighting and screens during the first few days to prevent photosensitivity reactions.
- Standard sunscreens won’t protect fully against light sensitivity, so it’s important to limit all light exposure during recovery.
- Apply a hydrating cream recommended by your specialist to soothe the treated area and prevent dryness or irritation.
- If you have a history of cold sores, follow your specialist’s advice regarding antiviral medications to prevent outbreaks triggered by the treatment.
- Avoid harsh skincare products such as exfoliants, retinoids, or acids during recovery, opting instead for gentle, fragrance-free products until your skin heals fully.
How Often Should I receive Photodynamic Therapy?
The frequency of photodynamic therapy (PDT) sessions depends on the condition being treated. For example, precancerous lesions or specific cancers may require several treatments over the course of weeks or months. On the other hand, conditions like acne or sun-damaged skin may need fewer sessions for effective results.
Because treatment plans are highly personalized, it’s important to consult with your healthcare provider to establish the optimal schedule based on your individual medical needs and desired outcomes.
Sources:
National Cancer Institute website. Photodynamic therapy to treat cancer. www.cancer.gov/about-cancer/treatment/types/photodynamic-therapy. Updated June 21, 2021. Accessed April 2, 2024.
