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Skin-cancer therapy gets OLED transformation

12 Dec 2006

A Scottish physics professor and a dermatology consultant have developed a new way of treating skin cancers with light-emitting bandages. Matthew Peach finds out about the technology, how it compares with other treatments and how it has performed in recent trials.

A light-emitting bandage, which it is claimed will transform the treatment of skin cancer, has been developed by scientists at the University of St Andrews and clinicians at Ninewells Hospital, Dundee (both Scotland, UK). Having developed the concept, Ifor Samuel and James Ferguson have established a company, Lumicure, to commercialize their invention.

The device, which builds on established photodynamic therapy (PDT) methods, is said to reduce pain and has the potential to be used by patients in their own homes. What's more, the researchers claim that the invention offers significant savings compared with existing PDT approaches.

Clinical trials

Ninewells has recently conducted a pilot clinical trial involving 12 patients with skin cancer and the results were promising. The light-emitting bandage was used to treat several varieties of non-melanoma skin cancer: basal cell carcinoma, squamous cell carcinoma in situ (Bowens disease) and actinic keratosis.

The patients were given two three-hour treatments. Each patient was reviewed three months after their second treatment and the cancer had cleared completely in nine out of the 12 cases.

"This will have a major impact on the treatment of skin cancers," Ferguson, head of Ninewells' Photobiology Unit, told OLE. "The light-emitting patch is a low-cost, portable and convenient method of treatment. Our initial pilot trials have already shown its effectiveness and we find patients requesting this treatment over conventional methods."

Treatments available

Existing treatments for pre-malignant and malignant skin disease are typically invasive and highly unpleasant, and can lead to secondary problems such as infections and scarring. Cryotherapy is widely used for small lesions but can lead to ulceration of the treatment area and has a poor cosmetic outcome. Surgical excision is also widely used and shows excellent efficacy but again the cosmetic outcome can be poor.

PDT is simply the combination of a light-sensitive pharmaceutical followed by irradiation with red light. Unlike the other treatments, PDT has an excellent cosmetic outcome. This is especially important as skin cancers tend to occur in areas that are exposed to sunlight, such as the face, hands and arms.

Treatment on the move

Samuel and Ferguson teamed up in 2002 to combine their respective expertise in light-emitting polymers and PDT with the aim of developing a new way to treat skin cancer. The end result was a portable, light-emitting bandage with a simple design.

The device comes in two parts: a small light-emitting plaster and a battery pack about the size of an iPod. The pharmaceutical typically comes in the form of a cream that is applied topically to the skin lesion. The cream is absorbed and is preferentially converted to a light-sensitive daughter compound within the tumour. The light-emitting plaster is then applied to the treatment site – this can be done at the doctor's surgery or even in the patient's home.

When red light is shone onto the area, a cell-destructive photoactive reaction occurs within the tumour leaving the surrounding healthy tissue untouched.

The PDT treatment takes three hours and, at the end of this time, the patient removes the plaster and disposes of the device. The battery is currently housed in a separate pack worn on a belt and attached to the plaster by a cable.

The red treatment light is generated by an organic light-emitting diode (OLED) and is a spin-off of Samuel's work on advanced displays. The OLED is custom-manufactured by Osram Opto Semiconductors of Germany for Lumicure. The source measures 25 × 25 × 1 mm and weighs 3 g. Its circular light-emitting area is 20 mm in diameter.

The OLED has a broad emission spectrum and emits between 500 and 800 nm having a peak around 650 nm. The brightness is typically 2500 cd/m2 for an input power of 1.35 W. The battery pack contains two microcontrollers: one to supply current to the OLED and the second for safety reasons to monitor for irregularities in case the first microcontroller fails.

According to the researchers, their light bandages work at lower light levels than conventional PDT sources and therefore the phototoxic reaction occurs at a much lower pain level. The OLED source is also said to be significantly cheaper than current laser sources used in PDT as well as being much less labour-intensive. The partners are currently working on a second device that will be a one-piece sticking plaster that will look and feel similar to current plasters used on cuts and grazes. Samuel, Ferguson and colleagues also believe that there are wider opportunities for the device such as treating acne and performing anti-aging treatments.

Commercial potential

To protect its invention, the Lumicure team has patented key aspects of the device. For example, it holds a patent that covers the use of OLEDs in lightweight portable PDT devices. A second patent relates to smart illumination of skin lesions to increase treatment efficacy.

Having secured an exclusive global licence to commercialize the device, the company is now looking for investment to take the working prototype further. Given estimates that around 10% of Scotland's population, or 500,000 people, will suffer from the disease at some point in their lifetimes, Lumicure certainly has a captive market for its product.

• This article originally appeared in the December 2006 issue of Optics & Laser Europe magazine.

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