Photodynamic Therapy (PDT)
The term “photodynamic therapy” or PDT refers to the interaction of light with a drug to achieve injury to targeted tissues that are cancerous or unhealthy. The drug itself may be light sensitive or may be quickly converted by the body to a light-sensitive product, which is then activated by a special light source. Once activated, the drug produces a controlled injury to the damaged tissue in which it is localized but does not exert an effect on normal, healthy tissue.
The Early Days of PDT
The application of PDT to cutaneous medicine initially arose from the treatment of certain skin cancers and “precancerous” growths. These studies were performed in Europe where PDT was first developed in 1913. A drug known as aminolevulinic acid (ALA) was applied to the skin where it quickly found its way into precancerous and certain cancerous tissues. The drug was initially allowed to set or “incubate” for 14 hours prior to activation by blue light. While highly effective, this process had some drawbacks in that patients would have to make visits to the office on two consecutive days, one to receive the drug and the next to have the drug activated. With exposure to sunlight, the drug is activated and patients would sometimes return to the office for activation even after the drug was already activated by incidental sunlight exposure. Subsequent studies demonstrated that incubation times as short as one hour may be sufficient to achieve desirable outcomes. This permits application, incubation, and activation of the drug during a single office visit.
Results from PDT Research
In a study submitted to the Food and Drug Administration (FDA) for approval of ALA in the United States, 243 patients with numerous precancerous areas on the face underwent treatment with ALA followed by activation with a special blue light.
- Nearly 80% of the precancerous growths were cleared by one treatment
- Approximately 10% more resolved with a second session
- 94% of patients noted improvement in the appearance of their skin following PDT treatment.
These results stimulated further investigation of ALA PDT in an expanded role as both an aesthetic treatment as well as a treatment for medical conditions.
Today, PDT is used for both medical and cosmetic treatments, from eliminating precancerous growths to treating difficult cases of acne.
Sun Damage and Precancerous Growths: For patients with extensive sun damage and a large number of precancerous growths, PDT is used for a medical benefit without particular attention to cosmetic improvement. In these cases, a portion of the expense is covered by most insurance companies. When the primary treatment goal is elimination of precancerous areas, a special blue light is used to activate the ALA. Blue light is used because this energy is more effective than any other at stimulating the PDT process. Blue light PDT can be used to treat the face, scalp, neck, chest, hands, arms and other areas.
Acne Treatments: PDT treatments are also useful in the treatment of acne. The ALA dye is actively absorbed by the oil-producing glands that play an important role in the development of acne blemishes. ALA-PDT treatments also kill the bacteria that have been implicated in causing acne breakouts. Traditional treatments such as Retin-A and other similar drugs, topical and systemic antibiotics, and in some situations hormonal therapy should remain the first line of treatment for acne. However, for those individuals whose acne is resistant to the standard therapies or who are unable to be fully compliant with the sometimes complex regimens required, PDT can be an excellent alternative. Patients undergoing PDT treatment for acne typically require three sessions spaced 2-4 weeks apart.
Cosmetic Improvement of Skin: PDT can be used to improve the appearance of sun damaged skin. When this endpoint is our goal, we often activate the Levulan using a combination of lights. Blue light is often used in conjunction with either intense pulsed light (IPL) or a pulsed dye laser (VBeam) to achieve improvement in skin quality, to reduce brown discoloration, and to reduce the redness that is often associated with sun damage. Blue light and pulsed via laser treatments are frequently performed during the same treatment session.
What to Expect during a PDT Treatment
- Microdermabrasion: Prior to beginning the PDT treatment, the area to be treated is prepared using the Vibraderm microdermabrasion device. This device gently polishes the skin, removing the dead cells that collect on the surface thereby enhancing penetration of ALA into the skin.
- ALA Application: The ALA is a clear solution that is applied quickly and without discomfort.
- Resting Period: A variable amount of time, typically from 30 to 90 minutes, will be allowed to elapse while the ALA is absorbed into the target area and chemically converted to a light-sensitive agent. During this time, you can relax quietly and comfortably. Exposure to the blue light typically requires an additional 10-20 minutes.
- Cleansing and Moisturizing: At the conclusion of this process the skin is gently cleansed and moisturizer and sunblock are applied. It is imperative that sun exposure be avoided for approximately 36 hours after application of the ALA as this can result in an exuberant response.
What to Expect after a PDT Treatment
The typical post treatment period after ALA-PDT involves a varying degree of redness, swelling and peeling that is often likened to sunburn. During this time most patients liberally apply moisturizer and sunblock. Some patients experience very little reaction, while those with more abnormal areas can have a more exuberant response. Those patients who have a dramatic reaction to the PDT treatment usually find that liberal application of Aquaphor Healing Ointment for several days keeps their skin moist and comfortable. The vast majority of patients find that their skin is back to normal approximately one week after treatment. Depending on the amount of sun damage present and the degree of reaction to the first PDT treatment, a second treatment session may be recommended 1-2 months after the first. Any abnormal appearing areas that persist despite PDT treatment will require either biopsy, treatment with topical agents such as Aldara, Carac, Efudex, Picato, or surgical excision.
Intense Pulsed Light Combined with Photodynamic Therapy (IPL-PDT)
IPL treatments are well known to improve the appearance of sun damaged skin by reducing brown and red discoloration. Four to six treatments are typically required to achieve the best outcomes. However, with the use of Levulan, the number of treatments required to achieve the best outcomes with IPL can be reduced as much is 50%. This means that you can achieve healthier skin with a more youthful appearance but fewer treatments if Levulan is used in conjunction with IPL therapy. The trade-off required to achieve this benefit is a slightly longer recovery time after each treatment but the results will be more dramatic and the total number of treatments fewer. As is true with all laser and light-based treatments, treatment should not be performed on patients who have any active infections in the treatment area or who are tanned in the treatment area.
Is PDT Treatment covered by Health Care Insurance?
In some situations, a portion of the costs of PDT therapy will be covered by insurance. However, in most scenarios at least some out-of-pocket expense should be anticipated.
- Photodynamic Therapy (PDT) uses a combination of medication and light to achieve a desirable outcome
- Levulan PDT treatments are usually used to treat precancerous growths and sun-damaged skin but may also be used to treat acne and to improve both the health and appearance of sun-damaged skin
- Treatments are performed in the office and do not require anesthesia or sedation
- Exposure to sunlight must be avoided for 24-36 hours after treatment as this will lead to uncontrolled activation of drug
- When treating precancerous growths and sun damage, 94% of patients have reported improvement in the skin’s appearance
- Any growths not responding to PDT may require treatment with either topical agents or surgical excision