Daylight versus conventional photodynamic therapy for the treatment of actinic keratosis: A meta-analysis of randomized controlled trials

Impact of light dose and fluence rate on the efficacy and tolerability of topical 5-ALA photodynamic therapy for actinic keratoses: A randomized, controlled, observer-blinded intrapatient comparison study

BACKGROUND

Conventional photodynamic therapy (cPDT) is an effective treatment option for field cancerization and multiple actinic keratoses (AK). The main side effect of cPDT is pain during illumination which in severe cases might necessitate early termination of treatment. Modification of treatment parameters such as light dose and fluence rate is a promising approach to mitigate PDT-associated pain.

OBJECTIVES

The aim of this study was to compare the efficacy and tolerability of four different cPDT illumination protocols in the treatment of AK in the head region.

METHODS

Prospective, investigator-blinded, within-patient study on 67 patients with multiple AK in the head region. PDT treatment was performed on comparable target areas with four different settings of illumination: (A) standard light dose and standard fluence rate, (B) standard light dose and halved fluence rate, (C) halved standard light dose and standard fluence rate and (D) halved standard light dose and halved fluence rate. Pain and the intensity of the phototoxic skin reaction was recorded during and after illumination. The clearance rate of the target areas and target lesions was assessed at 12 weeks after PDT. Target areas with incomplete clearance were retreated, those with complete clearance were reassessed at 24 weeks after PDT.

RESULTS

The mean and maximum pain level during illumination was significantly decreased at the lower fluence rates. The phototoxic skin reaction was most pronounced with the standard illumination setting. The overall clearance rate of AK and the clearance rate of the target lesions at 3 months after PDT as well as the number of recurrent or new AK at 6 months after PDT did not differ between four treatment protocols.

CONCLUSIONS

Reduction of the fluence rate and/or light dose was associated with less PDT-induced pain and/or shorter exposures times without compromising the therapeutic efficacy of cPDT for AK in the head region.

A Review of MAL-PDT for the Treatment Strategy of Actinic Keratosis: Broader Clinical Perspectives Beyond the Data and Guideline Recommendations

Methyl aminolevulinate (MAL) is a topical compound approved for use with photodynamic therapy (PDT) for the treatment of actinic keratosis (AK) and field cancerization in certain countries. There exists a high burden of disease for patients with AK: repeated treatments are required, there is a known risk of progression to keratinocyte carcinoma, and cosmetic appearance is affected. Delivery of PDT using MAL is a flexible treatment strategy available in many forms; red light, daylight, or artificial daylight can be used for illumination, all of which result in high AK clearance rates and low recurrence. MAL-PDT protocols continue to evolve to further improve adherence and treatment outcomes. Here, we used PubMed to search MEDLINE to identify guidelines, consensus recommendations, and studies describing the use of MAL for the treatment of AK. The aim of this targeted review is to consider various MAL-PDT treatment strategies on the basis of published literature, with a focus on personalizing treatment for the heterogeneous AK population.

Advances in Photodynamic Therapy for the Treatment of Actinic Keratosis and Nonmelanoma Skin Cancer: A Narrative Review

Photodynamic therapy (PDT) with photosensitization using 5-aminolevulinic acid (ALA) [including a nanoemulsion (BF-200 ALA)] is approved in the USA for the treatment of actinic keratoses (AKs); another derivative, methyl aminolevulinate, is not approved in the USA but is used in Europe. For AK treatment, the photosensitizer may be applied to individual AK lesions or, depending on treatment regimen, to broader areas of sun-damaged skin to manage field cancerization, although not all products are approved for field treatment. ALA-PDT and photosensitizers have also been used off-label for the treatment of nonmelanoma skin cancers, primarily basal cell carcinomas (BCCs) and cutaneous squamous cell carcinomas (cSCC). Advantages of PDT include potentially improved cosmesis and patient satisfaction; disadvantages include pain and duration of treatment. Alternative illumination approaches, including intense pulsed light as well as pulsed-dye lasers, have also been used successfully. Pretreating the affected tissue or warming during incubation can help to increase photosensitizer absorption and improve therapeutic efficacy. Combinations of multiple treatments are also under exploration. Reducing incubation time between photosensitizer application and illumination may significantly reduce pain scores without affecting treatment efficacy. Substituting daylight PDT for a conventional illumination source can also reduce pain without compromising efficacy. The objective of this narrative review is to describe current and ongoing research in the use of topical photosensitizers and modified light delivery regimens to achieve improved therapeutic outcomes with less toxicity in patients with AK, cSCC, BCC, and field cancerization.

The Role and Effectiveness of Photodynamic Therapy on Patients With Actinic Keratosis: A Systematic Review and Meta-Analysis

Actinic keratoses (AKs) are the most common neoplastic lesions and are recognized as a precursor to squamous cell skin cancer. Photodynamic therapy (PDT) is a therapeutic option for multiple AKs in line with field cancerization. The aim of this study was to assess the effectiveness of PDT on patients with AKs using a meta-analysis, in order to evaluate the possible superiority of one treatment over the others. For this purpose, the PubMed, MEDLINE, Scopus, OVID, Science Direct, British Journal of Dermatology, Research Gate, and Embase databases were searched in March 2022. The search terms used were 'photodynamic therapy' and 'actinic keratosis'. We utilized the random-effects meta-analysis model to compare methyl aminolevulinate PDT (MAL-PDT) and the combination of a nanoscale-lipid vesicle formulation with the prodrug 5-aminolevulinic acid (BF-200 ALA) on a complete response (CR) of the lesions. Our meta-analysis indicated that the comparison of BF-200 ALA versus MAL-PDT showed marginally higher CRs than MAL-PDT.

Management Pearls on the Treatment of Actinic Keratoses and Field Cancerization

Field cancerization (FC) is a chronic disease involving multiple clinical and subclinical actinic keratoses (AK) on large photo-exposed surfaces with multifocal areas of dysplasia and precancerous changes. Patients and treatment must be properly monitored and managed to avoid aggravation and progression of the disease. Management of actinic keratoses includes lesion-directed treatments, such as cryotherapy and field-directed therapies. Field-directed therapies may have the potential to address subclinical damage, reduce AK recurrence rates and potentially reduce the risk of squamous cell carcinoma development. Multiple studies have demonstrated the efficacy of field-directed treatments, including 5-fluorouracil, photodynamic therapy, imiquimod, chemical exfoliation with trichloroacetic acid and diclofenac gel, for multiple AK and FC. The choice of therapy should be based on multiple factors, such as efficacy, tolerability, patient risk profile, costs and cosmetic results. Management of AK includes not only treatment but also prevention. Medical devices, such as sunscreens containing liposome-encapsulated DNA repair enzymes, can repair DNA damage associated with chronic UV radiation and reduce the number of new AK lesions. Here we provide therapeutic pearls and expert opinions on the treatment of AK and FC (as monotherapy or in combination) with the overall aim to achieve better, faster, and well-tolerated clinical responses.

Italian expert consensus paper on the management of patients with actinic keratoses

Two round tables involving experts were organized in order to reach a consensus on the management of patients with actinic keratosis (AK). In the first, seven clinical questions were selected and analyzed by a systematic literature review, using a Population, Intervention, Control, and Outcomes framework; in the second, the experts discussed relevant evidences and a consensus statement for each question was developed. Consensus was reached among experts on how to best treat AK patients with respect to different clinical scenarios and special populations. Lesion-directed treatments are preferred in patients with few AKs. Patients with multiple AKs are challenging, with more than one treatment usually needed to achieve complete lesion clearance or a high lesion response rate, therapy should be personalized, based on previous treatments, patient, and lesion characteristics. Methyl aminolevulinate-PDT, DL (day light) PDT, and imiquimod cream were demonstrated to have the lowest percentage of new AKs after post treatment follow-up. For IMQ 5% and 3.75%, a higher intensity of skin reactions is associated with higher efficacy. Photodynamic therapy (PDT) is the most studied treatment for AKs on the arms. Regular sunscreen use helps preventing new AKs. Oral nicotinamide 500 mg twice daily, systemic retinoids and regular sunscreen use were demonstrated to reduce the number of new squamous cell carcinomas in patients with AKs. Limited evidence is available for the treatment of AKs in organ transplant recipients. There is no evidence in favor or against the use of any of the available treatments in patients suffering from hematological cancer.

Key factors affecting photoactivated fungicidal activity of sodium pheophorbide a against Pestalotiopsis neglecta

Recently, photodynamic therapy (PDT) and photoactivated pesticides have attracted considerable research attention. In the present study, we aimed to investigate the photodynamic activity of a chlorophyllous derivative, sodium pheophorbide a (SPA), and to evaluate its potential as a photoactivated fungicide. The singlet oxygen quantum yield, the photoreaction process, the anti-photobleaching ability in sterile water (H₂O), the effect of light conditions on its antifungal activity, and its stability were all investigated. SPA showed significant fungicidal activity and photostability, during which Type I and Type II photodynamic reactions occurred simultaneously on Pestalotiopsis neglecta, and the influence of Type I was slightly larger than that of Type II. In addition, light promoted the antifungal activity of SPA. In particular, the antifungal activity was enhanced with increasing light intensity, and was strongest under 8000 lx conditions. Under monochromatic light sources, antifungal activity was strongest under green light s; however, the effect of monochromatic light was not as good as that of white light. From 0 to 24 h, the antifungal effect of the SPA solution was enhanced; however, the activity of the solution began to weaken after 24 h. Furthermore, our study confirmed that the antifungal activity of SPA was stable under different temperatures, pH values, and UV irradiation durations.

Light Sources and Dosimetry Techniques for Photodynamic Therapy

Effective treatment delivery in photodynamic therapy (PDT) requires coordination of the light source, the photosensitizer, and the delivery device appropriate to the target tissue. Lasers, light-emitting diodes (LEDs), and lamps are the main types of light sources utilized for PDT applications. The choice of light source depends on the target location, photosensitizer used, and light dose to be delivered. Geometry of minimally accessible areas also plays a role in deciding light applicator type. Typically, optical fiber-based devices are used to deliver the treatment light close to the target. The optical properties of tissue also affect the distribution of the treatment light. Treatment light undergoes scattering and absorption in tissue. Most tissue will scatter light, but highly pigmented areas will absorb light, especially at short wavelengths. This review will summarize the basic physics of light sources, and describe methods for determining the dose delivered to the patient.

Clinical utility of daylight photodynamic therapy in the treatment of actinic keratosis - a review of the literature

Actinic keratosis (AK) is an early in situ squamous cell carcinoma that results from UV light exposure and has the potential to evolve into invasive tumor. Therefore, it is crucial that AKs are monitored and treated appropriately. Photodynamic therapy (PDT) is a treatment option that is minimally invasive and leaves patients with cosmetically superior results. However, disadvantages of PDT include pain and lengthy clinic visits. Accordingly, there has been much interest in the use of daylight photodynamic therapy (daylight-PDT) as a more convenient and less painful alternative to conventional photodynamic therapy (c-PDT). Current evidence shows that daylight-PDT is noninferior to c-PDT in the short and long term. Patients reported decreased pain with daylight-PDT and were more satisfied with the procedure (P<0.001). Current evidence suggests that 2 hrs of daylight exposure was sufficient for treatment, and its efficacy does not appear to be limited by weather conditions. Given the decreased intensity of treatment, daylight-PDT is better for mild disease, as it is less effective in moderate-to-thick AKs. Though further studies are still needed to refine the technique, daylight-PDT is a potential alternative to c-PDT for thin-to-moderate AKs and should be offered to patients with lower pain tolerance or busy schedules.

Prise en charge thérapeutique des kératoses actiniques

Dermatologists have many therapeutic options for the management of actinic keratoses (AK), in order to treat individual lesions or wider areas. Field cancerization is an area of sun-damaged skin, where visible and subclinical lesions co-exist, and is prone to the development of further AK lesions and sun-related skin cancers (SC). Treatments available are instrumental or medical. Resistance to treatment or atypical symptoms must lead to a biopsy for histological exam. Cryotherapy is the most frequently used method to destroy small or isolated AK, whereas photodynamic therapy (PDT), 5-fluoro-uracil (5-FU), imiquimod, ingenol mebutate and diclofenac are required for large, multiple lesions, and for the treatment of field cancerization. Side-effects of these therapies are essentially local, including pain, irritation, erythema, edema and scars. There is no randomized comparative study reviewing all these treatments, therefore physicians must also consider clinical characteristics, patient's compliance, side-effects and cost when treating AK. Medicoeconomic data of these treatments have been analyzed in several countries, and annual costs are estimated between 250 € and 2 000 €, with an uncertain cost-effective relation. Finally, beyond treatment of AK lesions, patients with AK are at high risk of developing SC, and must therefore have regular full-body examination, in order to be detected and treated precociously. © 2019 Elsevier Masson SAS. All rights reserved. Cet article fait partie du numéro supplément Kératoses actiniques : comprendre et traiter réalisé avec le soutien institutionnel de Galderma International.