Daylight Photodynamic Therapy for Actinic Keratoses

Abstract

Topical photodynamic therapy (PDT) using daylight is effective in the treatment of actinic keratoses (AKs), offering the potential for treatment of large fields such as full face and balding scalp, but with minimal therapy-associated pain. Comparison with conventional PDT indicates similar efficacy for thin and moderate-thickness AKs, but with significantly less discomfort/pain, driving a patient preference for daylight-mediated PDT (DL-PDT) compared with conventional PDT using high-intensity office/hospital-based light sources. Treatment protocol involves the application of a photosensitizing agent without occlusion and subsequent exposure to ambient daylight within 30 min, with patients exposed to daylight for 1.5-2.0 h. Pivotal randomized controlled trials in Europe and Australia have confirmed the efficacy of methyl aminolevulinic acid (MAL) DL-PDT in comparison with conventional MAL-PDT for mild and moderate-thickness lesions on the face and scalp. Initial clearance rates of 70-89% are reported. DL-PDT using a nanoemulsion aminolevulinic acid (ALA) has recently been shown to be at least as effective as MAL DL-PDT in treating mild and moderate-thickness AKs. DL-PDT may offer a better-tolerated method for treating patients with extensive AK disease. There is emerging literature on the potential for field PDT to reduce the number of new AKs developing, potentially preventing/slowing skin cancer development. Conventional PDT remains established as a therapy for Bowen's disease (squamous cell carcinoma in situ), superficial and certain thin basal cell carcinomas (BCCs), and AKs. The evidence for the use of DL-PDT beyond AK is limited, although has been reported in actinic cheilitis, superficial BCC, and acne and cutaneous leishmaniasis. There is emerging interest in combination therapy for AK, using one or more field therapies such as DL-PDT as an option to complement with localized treatment for residual lesions. We review current recommendations and consider the appropriate place for DL-PDT in our treatment armamentarium.

How promising is phototherapy for cancer?

“…In addition, pain and discomfort caused by red-light PDT can be significantly reduced using daylight PDT to treat precancerous skin lesions. 5 Daylight skin PDT can be performed using sunlight (>4-8 J/cm 2 ), but light devices are necessary for internal tumours, and for skin cancer in poor sunlight. 4 Lasers as PDT light sources offer high power output and easy connection to optical fibres and endoscopes, with precise light delivery to tumours in internal organs.…”

Photodynamic Therapy for Basal Cell Carcinoma: The Clinical Context for Future Research Priorities

“…It has been demonstrated that daylight can be sufficient to allow MAL-PDT to function; the effects of weather conditions, season, and latitude have been assessed, showing the potential of daylight-mediated PDT (DL-PDT). It is now a frequent method of topical PDT for superficial precancerous skin lesions, i.e., thin-moderate actinic keratoses (AK) of the head and neck [68]. The use of DL-PDT for BCC has been investigated in a case series of 21 patients/32 lesions, where, after the application of MAL but, unlike conventional PDT, without an intervening period of occlusion, the BCC were exposed for 2.5 h to daylight.…”

The Role of Erythroid Differentiation Regulator 1 (ERDR1) in the Control of Proliferation and Photodynamic Therapy (PDT) Response

“…As the time required to penetrate the skin is much longer during the cPDT process, the applied photosensitizers are mainly located in deep tissue where cutaneous nerves are found, which causes moderate to severe pain [29]. It seems that dPDT results in patient satisfaction because of the almost zero pain as well as excellent cosmetic results upon treatment [30,31]. Next, Ferrario et al suggested that targeting survivin, a Hsp-90 client protein, possibly improves PDT responses [32].…”