How does daylight PDT treatment compare to traditional and other types of treatments and therapies for actinic keratosis?

For years, sufferers of actinic keratoses (AK) had to choose between a range of topical applications and creams and very little else. While these creams initially showed some benefits in alleviating the condition, as soon as the applications were stopped, the condition tended to return. The development of daylight photodynamic therapy (DL-PDT) has brought a new methodology to treating this condition and others. But how does it work, and are the results positive or negative?

Actinic keratosis – symptoms and causes

Characterised by the thickening of the skin and the formation of crusty, scaly and thick skin patches, actinic keratosis is a disfiguring condition that can also be a precursor to malignant melanomas. The skin takes on a mottled or discoloured hue and, as the condition progresses, produces rough, scaly patches – not unlike psoriasis. It’s generally painless, but because it’s often found on the face and hands, it can be a distressing condition for patients to cope with. If left untreated, this skin condition can lead to squamous cell carcinoma.

The most common cause of actinic keratosis is prolonged exposure to UV light, either through excessive sunbed use or spending considerable time outdoors with little or no skin protection (e.g. sunscreens).

Current topical treatments

Various treatments are currently available, both on prescription and over the counter. However, the latter tend to be for very minor cases only and are often generic topical treatments for a range of skin conditions. So in most instances, creams are prescribed by a clinician. They may also recommend procedures such as curettage (where the damaged skin is scraped off) and electrosurgery (used to eliminate any remaining damaged tissue.)

Dietary and lifestyle changes can also affect the condition. If actinic keratosis is already prevalent on the skin surface, it may take some time for these actions to inhibit or reduce the instances of thickened skin.

Other alternatives involve cryotherapy, where the lesions are deep-frozen using liquid nitrogen. However, cryotherapy is only used in extreme conditions, and while it is a highly targeted process, there are concerns that it may inadvertently damage healthy tissue.

The alternative – d-PDT treatment

Daylight photodynamic therapy (dPDT) incorporates a new methodology for treating actinic keratosis. It’s simple, non-invasive, and has proven successful in clinical trials. Many institutions, including the NHS, now use it as the go-to treatment for actinic keratosis.

Like other treatments, it involves using a topical cream called prodrug on the affected area. This cream contains a photosensitizer (Protoporphyrin IX or PpIX) activated by natural daylight and then destroys the abnormal cells that are causing the skin’s surface to thicken or discolour. It is a very targeted treatment that only tackles the abnormal cells, leaving the healthy skin untouched.

Published data on the use of DL-PDT in conjunction with the standard use of topical cream demonstrated that not only was there an effective reduction in the occurrence of actinic keratosis of up to 79% within the treated area, compared to a 71% reduction in areas treated with cPDT. The

treatment was also less painful, according to test subjects.1 Once this specific trial had concluded, 18 out of the 29 subjects preferred the DL-PDT treatment regime compared to conventional PDT treatments.

Further studies have also demonstrated that daylight PDT is more practical, as patients can administer it themselves rather than attending a medical care centre for treatment. This makes DL-PDT a more appealing and logical form of treatment for actinic keratosis, provided the patient is given clear instructions on how to perform the treatment, also for avoiding any risk of sunburn. Regular consultations are recommended to ensure the patient is managing their condition correctly.

In conclusion

The use of DL-PDT compared to alternative methods such as cryotherapy and conventional PDT treatments has been shown to be effective, easy to manage, and less painful for the patient. Various studies have shown the increased effectiveness of dPDT therapy in conjunction with the appropriate topical applications.

Localised healthy tissue is undamaged by the process, and treatments can be carried out by the patient at home rather than attending a hospital or medical centre. This makes it more convenient, providing the patient with a better quality of life.