Can Advanced Light Source Technologies Revolutionize Photodynamic Therapy for Skin Cancer?

🔍 Key Finding Photodynamic therapy (PDT) using flexible light-emitting fabrics (FLEXI-PDT) demonstrates comparable efficacy to conventional PDT in treating actinic keratosis, with the added benefit of significantly reduced patient-reported pain. This suggests that light-emitting fabrics offer a promising, more comfortable approach to PDT for skin cancer.

🔬 Methodology Overview

• Design: Narrative review
• Data Sources: Published literature
• Selection Criteria: Focus on advanced light source technologies and delivery devices for photodynamic therapy (PDT) in skin cancer lesions. Includes discussion of photosensitizers, light sources, and advanced techniques like daylight PDT, metronomic PDT, fractionated PDT, and two-photon PDT.
• Analysis Approach: Qualitative synthesis of recent research and developments. Comparison of different light sources and techniques.
• Scope: Clinical application of PDT in skin cancer treatment, highlighting current limitations and future research directions.

📊 Results

• Skin Cancer Incidence: An estimated 5.4 million skin cancer cases are diagnosed yearly in the United States. Melanoma incidence in Spain is approximately 8.82 cases per 100,000 people/year, with a mortality rate of 2.17 per 100,000 people/year. Squamous cell carcinoma (SCC) incidence in Spain is estimated at 38.16 per 100,000 person-years.
• PDT for Actinic Keratosis (AK): Daylight PDT with methyl aminolevulinate (MAL) yields total lesion response rates >70% (grade I) in randomized trials, with minimal pain. Conventional PDT with MAL for AK shows clearance rates of 88-100% after 12 cycles, with 68-89% recurrence-free at 17-50 months follow-up.
• PDT for Basal Cell Carcinoma (BCC): PDT is approved in Europe for superficial BCC, with a 95% response rate among complete responders. PDT with MAL may offer similar lesion response rates to surgery or cryotherapy for BCC, but efficacy may be lower for nodular BCC.
• PDT for Squamous Cell Carcinoma (SCC): PDT is recommended for in situ SCC lesions. Clearance rates range from 88-100% after 12 PDT cycles with MAL, with no recurrence in 68-89% of treated lesions at 17-50 months follow-up. Limited evidence supports PDT effectiveness for invasive SCC.
• Flexible Light-Emitting Fabric PDT (FLEXI-PDT) for AK: Clinical trials (NCT03076892, NCT03076918) show FLEXI-PDT achieves comparable lesion clearance rates to conventional PDT (84% vs. 76.8% at 6 months) with significantly less patient-reported pain.
• Daylight PDT UV Exposure: Maximum average UV exposure during daylight PDT in the UK reached 8.2 standard erythemal doses (SED), while locations like Cyprus and Gibraltar experienced up to 14.3 SED and 12.9 SED, respectively, during June.

💡 Clinical Impact This review highlights advances in light delivery devices for photodynamic therapy (PDT), particularly light-emitting fabrics, which offer improved flexibility, comfort, and potentially better efficacy and tolerability compared to conventional methods, suggesting a shift towards more patient-friendly and potentially effective PDT for skin cancer. This could lead to wider adoption of PDT, especially for treating large or difficult-to-reach areas, improving patient experience and potentially treatment outcomes.

🤔 Limitations

• Inadequate penetration of topically applied photosensitizers for deep lesions.
• Lower efficacy of PDT for nodular BCC and invasive SCC.
• Variability in sunlight exposure for daylight PDT, impacting treatment efficacy.
• Risk of photosensitivity and skin damage with daylight PDT.
• Need for repeated treatments in metronomic PDT, increasing cost and inconvenience.
• Limited availability of two-photon compatible photosensitizers.
• Lack of standardized protocols and dosimetry for two-photon PDT.

✨ What It Means For You This research highlights advancements in light delivery devices for photodynamic therapy (PDT), offering doctors more flexible and potentially less painful treatment options for skin cancer, particularly for lesions on curved or irregular surfaces. The development of light-emitting fabrics and other conformable devices allows for better targeted treatment and improved patient comfort compared to traditional PDT methods, potentially increasing treatment accessibility and patient adherence.

Reference Algorri JF, López-Higuera JM, Rodríguez-Cobo L, Cobo A. Advanced Light Source Technologies for Photodynamic Therapy of Skin Cancer Lesions. Pharmaceutics. 2023;15:2075. https://doi.org/10.3390/pharmaceutics15082075