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S Ibbotson

Publications and source records attributed to S Ibbotson.

16 recordsLinked to original sources
PubMed2006

Clinical and research applications of photodynamic therapy in dermatology: experience of the Scottish PDT Centre.

BACKGROUND AND OBJECTIVES: The Scottish PDT Centre has carried out 3,442 treatments on 762 patients with superficial skin lesions, especially superficial basal cell carcinoma (sBCC), Bowen's disease (BD) and actinic keratosis (AK). STUDY DESIGN MATERIALS AND METHODS: The article reviews our experience of various light sources and associated dosimetry; thereafter we discuss clinical outcome followed by some of our research studies in clinically important areas. RESULTS: We show that improved dosimetry is required to ensure an optimal light dose is delivered to the tumour. We have shown that photosensitizers and proteins interact in such a way that their photophysical and photochemical properties are modified. We have also demonstrated the presence of DNA strand breaks with two different photosensitizers, but there is no evidence that PDT is significantly mutagenic in clinical practice. CONCLUSIONS: In our experience, topical PDT is generally well tolerated and is an effective treatment of sBCC, BD, AK, field change and lesions at sites of poor healing.

Aminolevulinic Acid↗
PubMed2006

Evidence-based practice of photopheresis 1987-2001: a report of a workshop of the British Photodermatology Group and the U.K. Skin Lymphoma Group.

Photopheresis or extracorporeal photochemotherapy (ECP) is a novel immunomodulatory therapy which involves separation of the patient's leucocyte-rich plasma, followed by ex vivo administration of a photosensitizer and ultraviolet A radiation, before reinfusion. ECP has been used successfully for the treatment of cutaneous T-cell lymphoma (CTCL: Sézary syndrome), graft-versus-host disease (GVHD) and cardiac transplant rejection. ECP has a dose-sparing effect on concurrent immunosuppressive therapy. The procedure induces apoptosis of the irradiated lymphocytes, but the exact mechanism by which ECP exerts its therapeutic effect in these different conditions is uncertain. The treatment has very few adverse effects and in particular is not associated with an increased incidence of opportunistic infections. The evidence for the efficacy of ECP has been appraised by a combined British Photodermatology Group and U.K. Skin Lymphoma Group workshop on the basis of evidence published up to the end of 2001 and on the consensus of best practice. There is fair evidence for the use of ECP in erythrodermic CTCL and steroid-refractory GVHD, but randomized controlled studies are needed. There is good evidence supporting the use of ECP in preventing cardiac rejection following transplantation. Randomized controlled trials have also shown a therapeutic benefit in type 1 diabetes mellitus, but the inconvenience associated with the procedure outweighed the clinical benefit. There is fair evidence not to use ECP for the treatment of systemic sclerosis and multiple sclerosis, and good evidence not to use ECP for other forms of CTCL.

Combined Modality Therapy↗
PubMed2006

Ambulatory photodynamic therapy: a new concept in delivering photodynamic therapy.

BACKGROUND: Photodynamic therapy (PDT) has been shown to be effective in treating Bowen's disease, superficial basal cell carcinoma and actinic keratosis. OBJECTIVES: To investigate the feasibility of delivering PDT using a portable light-emitting diode device. METHODS: A prototype diode array, comprising 37 AlGaInP diodes cast in epoxy with a diffuser, and driven by a battery pack, was designed and constructed. A pilot study was carried out in five patients with histologically proven Bowen's disease who were referred for PDT with 5-aminolaevulinic acid. They were all treated in the hospital-based dermatology PDT suite such that each received the same level of supervision as patients receiving PDT with nonambulatory light sources. Patients recorded pain levels. In accordance with our usual practice, patients received two treatments at a 4-week interval. RESULTS: Four of five patients were clear at follow-up (range 6-13 months, median 9). Pain was classified as none or mild in 80% of treatments and moderate in the remainder. CONCLUSIONS: There are many potential benefits of ambulatory PDT, including the possibility of a much higher patient throughput, and allowing effective treatment at home. This pilot study provides early promising data of the safety and efficacy of this approach.

Ambulatory Care↗
PubMed2002

Guidelines for topical photodynamic therapy: report of a workshop of the British Photodermatology Group.

Topical photodynamic therapy (PDT) is effective in the treatment of certain non-melanoma skin cancers and is under evaluation in other dermatoses. Its development has been enhanced by a low rate of adverse events and good cosmesis. 5-Aminolaevulinic acid (ALA) is the main agent used, converted within cells into the photosensitizer protoporphyrin IX, with surface illumination then triggering the photodynamic reaction. Despite the relative simplicity of the technique, accurate dosimetry in PDT is complicated by multiple variables in drug formulation, delivery and duration of application, in addition to light-specific parameters. Several non-coherent and coherent light sources are effective in PDT. Optimal disease-specific irradiance, wavelength and total dose characteristics have yet to be established, and are compounded by difficulties comparing light sources. The carcinogenic risk of ALA-PDT appears to be low. Current evidence indicates topical PDT to be effective in actinic keratoses on the face and scalp, Bowen's disease and superficial basal cell carcinomas (BCCs). PDT may prove advantageous where size, site or number of lesions limits the efficacy and/or acceptability of conventional therapies. Topical ALA-PDT alone is a relatively poor option for both nodular BCCs and squamous cell carcinomas. Experience of the modality in other skin diseases remains limited; areas where there is potential benefit include viral warts, acne, psoriasis and cutaneous T-cell lymphoma. A recent British Photodermatology Group workshop considered published evidence on topical PDT in order to establish guidelines to promote the efficacy and safety of this increasingly practised treatment modality.

Aminolevulinic Acid↗
PubMed2002

Guidelines for dosimetry and calibration in ultraviolet radiation therapy: a report of a British Photodermatology Group workshop.

This report examines the dosimetry of ultraviolet (UV) radiation applied to dermatological treatments, and considers the definition of the radiation quantities and their measurement. Guidelines are offered for preferred measurement techniques and standard methods of dosimetry. The recommendations have been graded according to the American Joint Committee on Cancer classification of strength of recommendation and quality of evidence (summarized in Appendix 5).

Humans↗
PubMed2001

The application of a compact multispectral imaging system with integrated excitation source to in vivo monitoring of fluorescence during topical photodynamic therapy of superficial skin cancers.

A novel, compact and low-cost multispectral fluorescence imaging system with an integrated excitation light source is described. Data are presented demonstrating the application of this method to in vivo monitoring of fluorescence before, during and after topical 5-aminolevulinic acid photodynamic therapy of superficial skin cancers. The excitation source comprised a fluorescent tube with the phosphor selected to emit broadband violet light centered at 394 nm. The camera system simultaneously captured spectrally specific images of the fluorescence of the photosensitizer, protoporphyrin IX, the illumination profile and the skin autofluorescence. Real-time processing enabled images to be manipulated to create a composite image of high contrast. The application and validation of this method will allow further detailed studies of the characteristics and time-course of protoporphyrin IX fluorescence, during topical photodynamic therapy in human skin in vivo.

Aminolevulinic Acid↗
PubMed2000

Guidelines for topical PUVA: a report of a workshop of the British photodermatology group.

Psoralen photochemotherapy [psoralen ultraviolet A (PUVA)] plays an important part in dermatological therapeutics, being an effective and generally safe treatment for psoriasis and other dermatoses. In order to maintain optimal efficacy and safety, guidelines concerning best practice should be available to operators and supervisors. The British Photodermatology Group (BPG) have previously published recommendations on PUVA, including UVA dosimetry and calibration, patient pretreatment assessment, indications and contraindications, and the management of adverse reactions.1 While most current knowledge relates to oral PUVA, the use of topical PUVA regimens is also popular and presents a number of questions peculiar to this modality, including the choice of psoralen, formulation, method of application, optimal timing of treatment, UVA regimens and relative benefits or risks as compared with oral PUVA. Bath PUVA, i.e. generalized immersion, is the most frequently used modality of topical treatment, practised by about 100 centres in the U.K., while other topical preparations tend to be used for localized diseases such as those affecting the hands and feet. This paper is the product of a recent workshop of the BPG and includes guidelines for bath, local immersion and other topical PUVA. These recommendations are based, where possible, on the results of controlled studies, or otherwise on the consensus view on current practice.

Administration, Oral↗
PubMed1999

The idiopathic photodermatoses.

The idiopathic photodermatoses present a challenge for dermatologists. Although, as in other specialty areas, the classical clinical presentation produces few problems, it is the severe forms and overlap cases that cause the most difficulty. It is fortunate that the semi-objective investigation of phototesting is available, which, when conducted carefully, reveals so much about the nature of this group of conditions. This essential investigation not only helps achieve a diagnosis, but also affords material for study and a means of monitoring therapy response or progress towards spontaneous resolution. Although these conditions are grouped together, throughout this century we have seen a continuing process of distinct diseases emerging as a consequence of careful clinical observation and investigation.

Age Factors↗
PubMed1995

Reduced experimental contact sensitivity in squamous cell but not basal cell carcinomas of skin.

Basal cell carcinomas (BCC) and squamous cell carcinomas (SCC) show clinical and epidemiological differences not accounted for by different ultraviolet radiation exposure. We have studied experimentally induced contact sensitivity to dinitrochlorobenzene by measuring increases in skin-fold thickness. Patients (n = 37) with squamous tumours had impaired responses compared with controls (33) and patients with BCCs (31) (mean increase 4.5 vs 7.8 and 8.6 mm, respectively; p = 0.002). This diminished immunological response may be causally related to the development of SCC. Because glutathione S-transferase (GST) metabolises dinitrochlorobenzene and polymorphisms of GST are associated with multiple skin tumours, variations in GST may underlie these differences.

Basal Cell Carcinoma↗