Comparison of protoporphyrin IX accumulation and destruction during methylaminolevulinate photodynamic therapy of skin tumours located at acral and nonacral sites

Abstract

Acral PDT 2 What's already known about this topic?Methyl-aminolevulinate photodynamic therapy (MAL-PDT) is known to be successful in the treatment of non-melanoma skin cancers (NMSC) and pre-cancerous lesions.However studies have demonstrated that efficacy of this treatment is reduced when these skin lesions are located on the body's extremities at acral sites. What does this study add?This study provides further evidence of the disparity between the response of dermatological skin lesions located at acral and non-acral sites to MAL-PDT treatment. For the first time this study monitors the changes in PpIX fluorescence during MAL-PDT treatment of (pre)cancerous skin lesions located within acral and non-acral sites. Comparison of changes in PpIX fluorescence within lesions at these sites furthers our understanding of the poorer response witnessed at acral sites. Acral PDT 3 AbstractBackground Topical photodynamic therapy is successful in the treatment of non-

Photodynamic Therapy in Bowen's Disease: Influence of Histological Features and Clinical Characteristics on Its Success

“…The outcome of PDT is variable and in some cases less successful compared to other treatment modalities such as surgical excision. Already known from the literature was that large BD lesions, multifocal BD and BD on body sites associated with poor wound healing are especially suitable for PDT treatment, although lower success rates can be expected on the lower extremities [4,5,7,13,17,18]. In our study we looked for different clinical and histological factors influencing PDT outcome in BD.…”

BritishAssociation ofDermatologists' guidelines for the management of squamous cell carcinomain situ(Bowen's disease) 2014

“…75 Body site does not appear to impact the efficacy of PDT, with protoporphyrin IX accumulation identical in SCC in situ located on acral and nonacral sites. 76 Digital SCC in situ was treated with ALA-PDT in four patients, with good cosmetic and functional results (one recurrence at 8 months responded to retreatment). 77 Case reports identify successful treatment of SCC in situ on the nipple, subungual, in poor healing sites on the lower legs, and in the setting of epidermolysis bullosa and radiation dermatitis.…”

The importance of iron chelation and iron availability during PpIX-induced photodynamic therapy

“…PDT can be advantageous in these situations and is associated with excellent cosmesis making it a particularly attractive treatment option for cosmetically conspicuous sites [17]. Standardised topical PpIX-PDT protocols utilising both ALA (Ameluz, Spirit Healthcare, UK) and MAL (Metvix, Galderma, UK) have been implemented within dermatology to good effect when the disease remains superficial [18], but improvement is required to treat thicker or acrally located conditions [19]. Many adaptations to standard treatment have been considered to improve efficacy including skin pre-treatment with the malignant cell differentiation potentiator dimethyl sulfoxide [20], skin stripping with tape [21], light dose fractionation [22,23], low fluence rate light administration [24] as well as combinations with other techniques such as low-dose Photofrin ® [25], hyperthermia [26,27], iontophoresis [28] and bioreductive drugs [29].…”