Daylight photodynamic therapy of actinic keratosis without curettage is as effective as with curettage: a randomized clinical trial

Home Self-Applied Daylight Photodynamic Therapy: Current Map in Spain and Management Proposals

OBJECTIVE

To determine the current practices of Spanish dermatologists performing home self-applied daylight photodynamic therapy (dPDT), and their experience with this treatment.

METHODOLOGY

We conducted a retrospective, multicenter, cross-sectional observational study with participation from 100 dermatologists from public and private Spanish hospitals. Their practices were collected through an online questionnaire and prepared based on a literature review, including experience, climatology, advantages, disadvantages and satisfaction with the self-applied dPDT.

RESULTS

A total of 38.4% of dermatologists have >5 years of experience using dPDT and 72.7% alternate consultation and home self-application. A total of 61.1% of dermatologists do not have specific protocols for self-application and 69.4% explain instructions to their patients personally. A total of 50% prefer to apply dPDT in months of greater solar activity and 70.8% recommend treatment during the morning. A total of 95.9% of the patients are satisfied or very satisfied with the treatment.

MAIN CONCLUSIONS

Self-applied dPDT is an effective and well-tolerated option to treat AK, especially in patients who adequately follow instructions and have family support. It is necessary to protocolize the self-applied dPDT to guarantee a greater safety and efficacy profile in the home application format.

Self-Applied Daylight Photodynamic Therapy: A Paradigm Shift?

Photodynamic therapy (PDT) involves the topical application of a photosensitizer and its activation by visible light, leading to the generation of protoporphyrin IX (PpIX) and reactive oxygen species. Daylight photodynamic therapy (dPDT), a variant utilizing natural sunlight as the energy source, enhances procedural flexibility by eliminating the need for specialized equipment. dPDT has been effectively used in dermatology to treat various cutaneous disorders, including neoplastic and infectious diseases. Traditionally, skin preparation and photosensitizer application are performed by trained practitioners, limiting the accessibility of dPDT for broader populations. However, recent studies suggest that these preparatory steps can be managed by patients or caregivers, enabling fully self-applied, home-based dPDT protocols. This review systematically examines the current evidence on self-applied dPDT (SA-dPDT), emphasizing molecular mechanisms and its efficacy in managing premalignant and other cutaneous conditions.

Daylight Photodynamic Therapy: At-Home Delivery

This pilot study evaluated the design, usability, and practicality of the dPDT@home kit for treating actinic keratoses (AKs) on the face and scalp. The kit allowed patients to manage their treatment at home, reducing hospital visits and utilizing natural sunlight. While patients were very willing to use the kit again, further studies are required to evaluate outcomes and ascertain the need for additional improvements and support. Background/Objectives: Daylight photodynamic therapy (dPDT) is an established effective therapy for superficial mild-to-moderate actinic keratoses (AKs) on the face and scalp. In this project, we redesigned the delivery of dPDT using design principles and the concept of Realistic Medicine to create the dPDT@home kit. This user-friendly and environmentally conscious kit allows patients to manage their AKs at home, reducing the need for hospital visits and ensuring timely treatment to coincide with appropriate weather conditions and to prevent disease progression due to delays in diagnosis and treatment. The initial pilot phase of the study was to evaluate the usability and convenience of the practicalities of the dPDT@home kit. Methods: Patients were instructed to conduct two dPDT@home kit treatments approximately three weeks apart on suitable weather days. After a follow-up telephone consultation from the specialist PDT nurse following the first treatment, patients then completed an initial questionnaire (Questionnaire 1, Q1) to share their experience. A second questionnaire (Q2) was completed 3-6 months after their final treatment to assess treatment outcomes. Results: A total of 16 patients with AK on the face and/or scalp used the dPDT@home kit. Five patients formed an initial pilot group in 2020/21, whose feedback and involvement informed the final product for the larger group of eleven patients (2021/22). All patients reported no issues with receiving the kit or the pro-drug used in the treatment (Q1). Q2 had an 81.25% return rate, with an average willingness score of 8.9/10 to use dPDT@home again. However, patients expressed doubts about their confidence in the treatment's efficacy, giving an average score of 6.9/10, with preferences leaning towards other treatments, such as hospital-based PDT or cryotherapy. Conclusions: The pilot deployment of the dPDT@home kit identified suitable patients and highlighted the need for comprehensive training and support for both patients and clinicians to deliver dPDT through this novel approach. The kit can reduce the number of hospital visits, but patients still require supervision, which can be provided remotely. The questionnaire outcomes emphasize the importance of setting patient expectations and taking a holistic approach to managing chronic field-change AK. Additionally, the kit's recyclable components and reliance on natural sunlight promote sustainability and reduce patient travel. Further evaluation is required to determine cost-efficacy, safety, and the potential place of the dPDT@home kit in the therapeutic management of patients with this common and challenging condition.

The use of photodynamic therapy in medical practice

Cancer therapy, especially for tumors near sensitive areas, demands precise treatment. This review explores photodynamic therapy (PDT), a method leveraging photosensitizers (PS), specific wavelength light, and oxygen to target cancer effectively. Recent advancements affirm PDT's efficacy, utilizing ROS generation to induce cancer cell death. With a history spanning over decades, PDT's dynamic evolution has expanded its application across dermatology, oncology, and dentistry. This review aims to dissect PDT's principles, from its inception to contemporary medical applications, highlighting its role in modern cancer treatment strategies.

Home- vs clinic-based daylight photodynamic therapy with 5-aminolevulinic acid nanoemulsion (BF-200 ALA) for actinic keratosis: A randomized, single-blind, prospective study

BACKGROUND

Daylight photodynamic therapy (DL-PDT) has become one of the most effective treatments for the resolution of actinic keratosis (AK) of Olsen grade 1 and 2. Generally, PDT it is carried out in a clinic setting, which involves the patient's and their caregivers commuting to the hospital as well as a significant use of resources to carry it out within the clinic setting.

OBJECTIVES

To determine the efficacy and safety of a home-based treatment of AK with DL-PDT with the BF-200 ALA gel compared to a clinic-based setting.

METHODS

The study was performed as a randomized, single-center, non-inferiority clinical trial with two parallel groups. 9 patients received one clinic-based DL-PDT (group 1) and 11 patients received one session of home-based DL-PDT (group 2). The primary endpoints were the mean AK clearance per patient and the total AK lesion clearance rate 12 weeks after treatment. The secondary endpoints were the number of remaining AKs and new AKs appearing in the treatment field 12 weeks after one PDT session. The pain during and 24 h after PDT as well as the local skin reactions were also assessed.

RESULTS

The overall reduction of AK lesions per patient was similar in both groups with one PDT session. An overall AK clearance per patient of 10 ± 4.33 for group 1 versus 9.73 ± 2.9 for group 2 without statistically significant differences (p = 0.868). Regarding the clearance rate, although it was slightly higher in group 2 (71.58 ± 22.51 vs 82.1 ± 11.13), the analysis did not show statistically significant differences. The mild pain recorded during the treatment course and the mild local skin reactions were similar in both groups. Patient satisfaction was high for both groups without statistically significant differences.

CONCLUSION

Self-performed home-based DL-PDT with BF-200 ALA gel is as effective as the one performed in a clinic-based setting, with a comparable safety profile, high levels of patient satisfaction and with advantages for the patients and their caregivers that can enhance patient´s adherence to the treatment.

Keratolytics can replace curettage in daylight photodynamic therapy for actinic keratosis on the face/scalp: A randomized clinical trial

BACKGROUND

Methyl aminolevulinate (MAL) photodynamic therapy (PDT) is commonly used for field treatment of actinic keratoses (AKs). In standard natural daylight PDT (n-DL-PDT) the first step, after the application of chemical solar filter, is removal of crusts and scales by curettage, followed by the application of MAL cream. Some patients experience intense pain during curettage and stinging after application of the photosensitizer to just curettaged skin.

OBJECTIVES

To evaluate whether n-DL-PDT without curettage, but preceded by application of keratolytics, would maintain a similar efficacy, based on clinical, dermoscopic, reflectance confocal microscopy (RCM) assessments, safety and patient satisfaction as standard n-DL-PDT with curettage.

METHODS

Forty patients with multiple AKs on the face and/or scalp were enrolled in this study. Patients were randomized into two groups of treatment as follows: (i) MAL n-DL-PDT without previous curettage, preceded by skin preparation at home with keratolytics (30% urea cream, twice a day for 7 days; -Cur group) and (ii) MAL n-DL-PDT preceded by skin preparation at the hospital with curettage (+Cur group).

RESULTS

Thirty-nine participants completed the study. Four hundred and twenty-one AKs in -Cur group and 337 AKs in +Cur group were treated. The mean reduction in the number of AK lesions 3 months after the treatment was 10.7 (-54.7%) in the -Cur and 10.4 (-58.7%) in the +Cur group. We found that the differences in terms of efficacy and patient satisfaction comparing the two treatment regimens were not statistically significant. The pain score reported during and after daylight exposure was similar and low in both groups. Moreover, no unexpected adverse events occurred during the trial period.

CONCLUSIONS

According to our results, curettage is not necessary to obtain the full treatment effect of n-DL-PDT. We experienced in a real-life setting that n-DL-PDT protocol could be changed by replacing curettage with keratolytics.

A Review of the Dermatologic Clinical Applications of Topical Photodynamic Therapy

Topical photodynamic therapy is a widely approved therapy for actinic keratoses and low-risk nonmelanoma skin cancers with a rapidly growing range of emerging indications for other cutaneous diseases. This review summarizes the best-available evidence to provide a clinical update for dermatologists on the approved and emerging indications of photodynamic therapy. The body of evidence suggests that photodynamic therapy is superior or noninferior to other available treatment modalities for actinic keratoses, low-risk basal cell carcinomas, Bowen's disease, skin field cancerization, chemoprevention of keratinocyte carcinomas in organ transplant recipients, photoaging, acne vulgaris, and cutaneous infections including verrucae, onychomycosis, and cutaneous leishmaniasis. There is emerging evidence that photodynamic therapy plays a role in the management of actinic cheilitis, early-stage mycosis fungoides, extramammary Paget disease, lichen sclerosis, and folliculitis decalvans but there are no comparative studies with other active treatment modalities. Common barriers to topical photodynamic therapy include procedural pain, costs, and the time required for treatment delivery. There is significant heterogeneity in the photodynamic therapy protocols reported in the literature, including different photosensitizers, light sources, number of treatments, time between treatments, and use of procedural analgesia. Topical photodynamic therapy should be considered in the management of a spectrum of inflammatory, neoplastic, and infectious dermatoses. However, more comparative research is required to determine its role in the treatment algorithm for these dermatologic conditions and more methodological research is required to optimize photodynamic therapy protocols to improve the tolerability of the procedure for patients.

Is a 4 J/cm2 PpIX-Weighted Simulated Daylight (SDL-PDT) Dose Still Efficient for Photodynamic Therapy of Actinic Keratosis?

Background: Several solutions are now proposed to provide indoor illumination with so-called artificial white light or simulated daylight (SDL-PDT), resulting in an effective treatment for actinic keratosis (AK). However, the optimal PpIX-weighted light dose is still debated. Integrating the effective irradiance over the irradiation time yields the effective light dose, which is also known as the protoporphyrin IX-weighted light dose and is a key parameter for the efficacy of the treatment. Objectives: The paper aims to report the clinical outcomes of SDL-PDT when using the PpIX-weighted light dose of 4 J/cm2, in patients treated for AK lesions of the scalp or the face at our medical dermatology center (ClinicalTrials.gov NCT052036). Methods: A total of 30 patients (16 males, 14 females), with a mean age of 71.0 ± 10.2, with phototype 1 (16 patients) and phototype 2 (14 patients) with grade I-II AK were treated with a drug light interval (DLI) of 10 min and a light exposure of 35 min (Dermaris, Surgiris, Croix, France), corresponding to a PpIX-weighted light dose of 4 J/cm2. The primary endpoint was the cure rate of patients at six months post-treatment. Secondary endpoints included scores of pain, erythema, crusts, and discomfort during or/and post the treatment. Results: In total, 762 AK were treated. Six months following treatment, the cure rate of the patients was 77%. The median pain score was less than 1 out of 10 for most of the patients. Erythema was observed in all patients and lasted 3 days (±1.5 day). Crusts were seen in 28 patients. Discomfort was reported as mild or less in more than 97% of patients. Conclusions: The shortening of the PpIX-weighted light dose to 4 J/cm2, corresponding to an illumination duration of 35 min with the Dermaris, does not modify the efficacy of the SDL-PDT. This observation is in agreement with recent published data demonstrating that the light dose can be reduced. Furthermore, this clinical study confirmed that SDL-PDT is an effective and nearly painless treatment with minimal side effects for patients with AK lesions of the scalp.

The role of the light source in antimicrobial photodynamic therapy

Antimicrobial photodynamic therapy (APDT) is a promising approach to fight the growing problem of antimicrobial resistance that threatens health care, food security and agriculture. APDT uses light to excite a light-activated chemical (photosensitiser), leading to the generation of reactive oxygen species (ROS). Many APDT studies confirm its efficacy in vitro and in vivo against bacteria, fungi, viruses and parasites. However, the development of the field is focused on exploring potential targets and developing new photosensitisers. The role of light, a crucial element for ROS production, has been neglected. What are the main parameters essential for effective photosensitiser activation? Does an optimal light radiant exposure exist? And finally, which light source is best? Many reports have described the promising antibacterial effects of APDT in vitro, however, its application in vivo, especially in clinical settings remains very limited. The restricted availability may partially be due to a lack of standard conditions or protocols, arising from the diversity of selected photosensitising agents (PS), variable testing conditions including light sources used for PS activation and methods of measuring anti-bacterial activity and their effectiveness in treating bacterial infections. We thus sought to systematically review and examine the evidence from existing studies on APDT associated with the light source used. We show how the reduction of pathogens depends on the light source applied, radiant exposure and irradiance of light used, and type of pathogen, and so critically appraise the current state of development of APDT and areas to be addressed in future studies. We anticipate that further standardisation of the experimental conditions will help the field advance, and suggest key optical and biological parameters that should be reported in all APDT studies. More in vivo and clinical studies are needed and are expected to be facilitated by advances in light sources, leading to APDT becoming a sustainable, alternative therapeutic option for bacterial and other microbial infections in the future.

Global Trends and Research Progress of Photodynamic Therapy in Skin Cancer: A Bibliometric Analysis and Literature Review

Background

Based on photochemical reactions through the combined use of light and photosensitizers, photodynamic therapy (PDT) is gaining popularity for the treatment of skin cancer. Various photosensitizers and treatment regimens are continuously being developed for enhancing the efficacy of PDT on skin cancer. Reviewing the development history of PDT on skin cancer, and summarizing its development direction and research status, is conducive to the further research.

Methods

To evaluate the research trends and map knowledge structure, all publications covering PDT on skin cancer were retrieved and extracted from Web of Science database. We applied VOSviewer and CiteSpace softwares to evaluate and visualize the countries, institutes, authors, keywords and research trends. Literature review was performed for the analysis of the research status of PDT on skin cancer.

Results

A total of 2662 publications were identified. The elements, mechanism, pros and cons, representative molecular photosensitizers, current challenges and research progress of PDT on skin cancer were reviewed and summarized.

Conclusion

This study provides a comprehensive display of the field of PDT on skin cancer, which will help researchers further explore the mechanism and application of PDT more effectively and intuitively.

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.

Clinical evaluation of a short illumination duration (1 hour) when performing photodynamic therapy of actinic keratosis using the Dermaris light source

BACKGROUND

Photodynamic therapy (PDT) using daylight as the photoactivating light source (DL-PDT) is an effective treatment for actinic keratosis (AK). Among the artificial daylight sources, the Dermaris (Surgiris, Croix, France) is specially designed for SDL-PDT (simulated daylight PDT) of AK. To perform the PDT session, a long duration (2.5 h) and low-intensity light exposure (2.9 mw/cm²) is used. This long duration is considered as a major limitation by both the patient and the dermatologist.

OBJECTIVES

The paper aims to report the clinical outcomes of SDL-PDT using the Dermaris in patients treated for AK lesions of the scalp at our medical dermatology center using only one hour low-intensity light exposure.

METHODS

Thirty patients (19 males, 11 females), mean age: 72.8 ± 9.3, with phototype 1 (11 patients), with phototype 2(17 patients) and phototype 3 (2 patients), with grade I-II AK of the scalp were treated with a drug-light interval (DLI) of 10 min and a light exposure of 1 h. The cure rate of AK lesions at six months after the treatment was determined. Erythema, crusts, discomfort and during or/and post the treatment were also evaluated.

RESULTS

In total, 293 AK were treated. Six months following treatment, the cure rate of patients was 93%. Pain score reported after the first PDT session was from 0 to 1 on a visual analogue scale (VAS) ranging from 0 to 10. Erythema was observed in 28 patients and lasted 3 days, crusts were seen in 19 patients. Discomfort was as mild or less in more than 97% of patients.

CONCLUSIONS

the shortening of the exposure time to one hour does not modify the efficacy of the SDL-PDT using the Dermaris. This observation is in agreement with recent published data demonstrating that PDT can be performed successfully with half the illumination time used in daylight PDT today. Besides, this clinical study confirmed that SDL-PDT is an effective and nearly painless treatment with minimal side effects for patients with AK lesions of the scalp.

Chinese guidelines on the clinical application of 5-aminolevulinic acid-based photodynamic therapy in dermatology (2021 edition)

Photodynamic Therapy with 5-aminolevulinic acid (ALA-PDT) has been widely applied in the treatment of skin diseases in China. To further standardize, guide, and promote the clinical applications of ALA-PDT in dermatology, the Chinese Society of Dermatology, Chinese Association of Rehabilitation Dermatology, Photomedicine Therapeutic Equipment Group of Committee on Skin Disease, and Cosmetic Dermatology of China Association of Medical Equipment invited relevant experts engaged in ALA-PDT to revise and update the first edition of "Clinical application of 5-aminolevulinic acid-based photodynamic therapy: an expert consensus statement" and establish a more current edition, to provide an updated reference for Chinese dermatologists in clinical practice. In the guideline, the expert group reached consensus opinions on ALA-PDT with regard to mechanisms of action, therapeutic protocol, clinical applications, adverse reactions and countermeasures, precautions, care, and evaluation of efficacy.

Painless Photodynamic Therapy Triggers Innate and Adaptive Immune Responses in a Murine Model of UV-induced Squamous Skin Pre-cancer

Painless photodynamic therapy (p-PDT), which involves application of photosensitizer and immediate exposure to light to treat actinic keratosis (AK) in patients, causes negligible pain on the day of treatment but leads to delayed inflammation and effective lesion clearance (Kaw et al., J Am Acad Dermatol 2020). To better understand how p-PDT works, hairless mice with UV-induced AK were treated with p-PDT and monitored for 2 weeks. Lesion clearance after p-PDT was similar to clearance after conventional PDT (c-PDT). However, lesion biopsies showed minimal cell death and less production of reactive oxygen species (ROS) in p-PDT treated than in c-PDT-treated lesions. Interestingly, p-PDT triggered vigorous recruitment of immune cells associated with innate immunity. Neutrophils (Ly6G+) and macrophages (F4/80+) appeared at 4 h and peaked at 24 h after p-PDT. Damage-associated molecular patterns (DAMPs), including calreticulin, HMGB1, and HSP70, were expressed at maximum levels around 24 h post-p-PDT. Total T cells (CD3+) were increased at 24 h, whereas large increases in cytotoxic (CD8+) and regulatory (Foxp3+) T cells were observed at 1 and 2 weeks post-p-PDT. In summary, the ability of p-PDT to eliminate AK lesions, despite very little overt cellular damage, appears to involve stimulation of a local immune response.

Actinic keratoses contiguous with squamous cell carcinomas are mostly non-hyperkeratotic and with severe dysplasia

AIMS

Actinic keratosis (AK) is a precursor of cutaneous squamous cell carcinoma (SCC). No validated parameters can predict which AKs will progress into SCCs, but especially thick AKs are under suspicion. The clinical and histopathological thickness of AKs is strongly correlated. This study aimed to investigate the thicknesses and degree of dysplasia of AKs contiguous with SCCs assuming these AKs represent the AKs that have undergone malignant transformation.

METHODS

Files of the Pathology Department, Hospital of Southern Jutland, Denmark, were reviewed. 111 cases met the inclusion criteria: a skin biopsy containing an invasive SCC. All SCCs merged with an AK at the edge. Degree of dysplasia, epidermal thickness and stratum corneum thicknesses of AKs were measured.

RESULTS

All AKs showed severe dysplasia. Most AKs had a stratum corneum thickness under 0.1 mm and an epidermal thickness under 0.5 mm, corresponding to clinically thin and non-hyperkeratotic AKs.

CONCLUSIONS

Our result suggests malignant progression potential of AKs regardless of thickness.

How Much Protoporphyrin IX Must Be Activated to Obtain Full Efficacy of Methyl Aminolevulinate Photodynamic Therapy? Implication for Treatment Modifications

Photodynamic therapy (PDT) with methyl aminolevulinate (MAL) is a popular treatment for actinic keratoses (AK), and several PDT treatment modalities with similar cure rates are in use. The effect relies on the activation of protoporphyrin IX (PpIX) in premalignant cells. This study aimed to measure PpIX during each treatment modality to determine the minimal PpIX activation and shortest exposure time for optimal cure rate. In four different treatment modalities, we established the PpIX formation up to three hours after MAL application without illumination and measured the speed of PpIX photoactivation during 9 min of red light (37 J/cm²). The level of PpIX three hours after MAL application was set to 100 PpIX units. In comparison, 85 PpIX units were formed during daylight PDT, 57 PpIX units during pulse PDT, and 52 PpIX units without any curettage prior to MAL. The activation of 50 PpIX units should, therefore, be enough to obtain a full effect on AK. Further, red light illumination may be shortened from 9 min to 1–2 min. The results indicate that PDT can be performed successfully with half the illumination time used in daylight PDT today and with one fourth of the illumination time used in classical PDT.

Daylight Photodynamic Therapy: An Update

Daylight photodynamic therapy (dPDT) uses sunlight as a light source to treat superficial skin cancer. Using sunlight as a therapeutic device has been present for centuries, forming the basis of photodynamic therapy in the 20th century. Compared to conventional PDT, dPDT can be a less painful, more convenient and an effective alternative. The first clinical uses of dPDT on skin cancers began in Copenhagen in 2008. Currently, aminolevulinic acid-mediated dPDT has been approved to treat actinic keratosis patients in Europe. In this review article, we introduce the history and mechanism of dPDT and focus on the pros and cons of dPDT in treating superficial skin cancers. The future applications of dPDT on other skin diseases are expected to expand as conventional PDT evolves.

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.

Measuring Daylight: A Review of Dosimetry in Daylight Photodynamic Therapy

Successful daylight photodynamic therapy (DPDT) relies on the interaction of light, photosensitisers and oxygen. Therefore, the 'dose' of light that a patient receives during treatment is a clinically relevant quantity, with a minimum dose for effective treatment recommended in the literature. However, there are many different light measurement methods used in the published literature, which may lead to confusion surrounding reliable and traceable dose measurement in DPDT, and what the most appropriate method of light measurement in DPDT might be. Furthermore, for the majority of practitioners who do not carry out any formal dosimetry and for the patients receiving DPDT, building confidence in the evidence supporting this important treatment option is of key importance. This review seeks to clarify the methodology of DPDT and discusses the literature relating to DPDT dosimetry.