Photodynamic Therapy

Daylight PDT consultation
Photodynamic therapy involves light activation of a tissue-localised photosensitiser in the presence of oxygen and may be used for the treatment of many diseases, usually malignancies, in several different organs.

The Scottish Photodynamic Therapy Centre

The Scottish Photodynamic Therapy Centre was officially opened by Princess Alexandra at Ninewells Hospital, Dundee in 2001 and for six years, this was entirely funded by the Barbara Stewart Cancer Trust, and still receives generous support from the Alf Stewart Trust.

The Centre has the primary objective of providing Photodynamic Therapy (PDT) for malignant and pre-malignant conditions affecting a range of organs, and of promoting the use and development of photodiagnosis (PDD) for the early detection of cancer.

The Centre has carried out over 11,500 treatments, treating patients from all over Scotland and from elsewhere in the UK and abroad. The majority of PDT treatments are for skin malignancies and pre-malignancies as there have been huge advances in dermatological PDT, which have been helped by the accessibility of skin to drug application and light delivery.

The Centre has also completed successful studies of PDT for bile duct and brain tumours and we continue to investigate photodiagnostic techniques in the bladder and urinary tract. Diagnostic assisted surgical procedures in brain tumours are also ongoing.

The Centre undertakes an active research programme with numerous publications in peer- reviewed journals. Advice is provided to government and other organisations on the role of PDT and PDD in the diagnosis and treatment of cancer.

PDT in Dermatology

Chronic sun exposure is the main environmental risk factor for skin cancer development and sun damage. PDT is a treatment for certain skin tumours (superficial basal cell carcinoma); sun damaged skin (Bowen’s disease, actinic keratosis) and some other skin conditions, such as viral warts and some cases of acne. This technique involves activation of a tissue- localised photosensitiser by visible (red) light in the presence of oxygen.

Treatment penetrates to 1-2mm in skin so is useful for superficial skin cancers and sun damage. On being referred for PDT the patient is generally seen by a Dermatologist to determine a treatment plan depending on the diagnosis, and treatment is performed by technical or nursing staff. A typical treatment regime is two treatments on consecutive weeks followed up by review at three months (plus a second treatment cycle if not clear) and one year.

How is the therapy given?

A specific cream is applied to the area to be treated and then covered with an occlusive dressing and left in place for 3-6 hrs. The chemical 5-aminolaevulinic acid (5-ALA; Ameluz) or the methyl ester of 5-ALA (MAL; Metvix) in the cream is taken up by the abnormal skin cells and is converted to a light sensitive chemical (photosensitiser) within the cells.

A powerful red light (usually an LED) is then shone on the treated area to activate the chemical, which then kills the abnormal cells, eventually leading to necrosis. Immediately post treatment a dressing is placed over the treated site and left on for 24hrs as the area becomes inflamed, although this usually settles over a week. The outcome with PDT is generally cosmetically better than with alternative treatments.

Ambulatory PDT

One drawback of PDT is that the patients can experience discomfort and pain during the red light irradiation (usually only a few minutes), although this is highly variable. There is preliminary evidence that low irradiance PDT, delivered by a portable lightweight battery-powered device (Ambulight) allowing treatment at home, may be more effective and less painful than conventional PDT. Indeed if this is the case, then this would significantly improve the patient’s experience of PDT and successful delivery and wide acceptance of this therapy. We have recently completed a randomised controlled trial in the Photobiology Unit comparing both treatments in a total of fifty patients and the results will inform our future practice.

Daylight PDT

We have also used daylight PDT in the spring and summer months, since 2013 and this has been extremely well tolerated and received by patients and is showing high efficacy rates, whilst being a virtually painless treatment approach. We have led the way in introducing daylight PDT in the UK and we are recognised as a daylight PDT training centre in the UK and elsewhere in Europe.

Euro-PDT

Professor Sally Ibbotson was presented with the award of Euro-PDT Specialist in September 2015 and the Photobiology Unit received accreditation as the first UK Euro-PDT Centre of Excellence at the same time. This greatly strengthens our role in research, training and teaching in PDT.
Centre of Excellence award for NHS Tayside Photobiology Unit

Euro-PDT Centre of Excellence Award for Photobiology Unit

HM Queen Elizabeth II black and white
NHS Tayside Logo White
Her Majesty Queen Elizabeth II

1926 - 2022