Basal cell carcinoma (BCC) is the most common skin cancer in humans, and its global incidence continues to rise. This disease develops from cells that line the bottom of the skin’s top layer and almost always occurs in areas exposed to the sun, notably the head and neck, and most of the rest on the trunk, arms, and legs.
Typically, a BCC lesion start off looking like a harmless blemish that persists or bleeds easily and won’t heal completely. Most of these lesions are slow-growing only rarely spread or metastasize. The main cause is thought to be intensive exposure to the sun’s ultraviolet rays during childhood and adolescence.
There are two major types of BCC. The most common type, called nodular BCC, usually shows up as a shiny bump on the face, scalp, neck or ears. This type can bleed easily and often ulcerates before then crusting over and creating the misperception that it’s healing. The other common type, called superficial BCC, is so named because it occurs in the upper level of the skin, usually on the back as a red, scaly, sometimes itchy spot that’s often mistaken for a patch of dermatitis.
Photodynamic therapy, or PDT, is among the treatments that has been used successfully for superficial BCC. This approach uses a light-sensitizing drug and a visible light source, such as a laser or LED light. When treating skin cancer, the drug (photosensitizing agent) is typically applied to the skin as a cream, whereupon it is absorbed by the body’s cells, making them sensitive to light. When the area is then “treated” with light, the cancer cells are damaged and ultimately destroyed.
Combining PDT with Surgery for Nodular BCC
To further improve photodynamic strategies for treating BCC, researchers from the University of Copenhagen (Denmark) recently collaborated with the Wellman Center for Photomedicine at Harvard Medical School in Boston, Massachusetts (USA). PDT has been approved in the United States for the treatment of selected nodular BCCs, but its efficacy is thought to be fairly limited when it comes to treating large and thick tumors.
To overcome this limitation, the research team opted to use ablative fractional lasers to enhance the uptake of the photosensitizing agent and thus improve the treatment’s outcome. Fractional laser therapy has been favored for treating various skin conditions in the past because of its more favorable post-treatment effects on the skin—typically resulting in a smoother, softer, more even-looking skin)—when compared to other laser treatment strategies.
The study enrolled 32 patients with high-risk tumors that had a a diameter greater than 15 millimeters, as well as those BCC tumors located in high-risk zones or on severely sun-damaged skin. After the tumors were surgically debulked, the patients were randomly assigned to one of two groups—either PDT alone or PDT with the fractional laser therapy.
After three months, the clinical cure rates were 100% for the PDT plus fractional laser group compared to 88% for PDT alone. In addition, recurrences tended to occur later. After one year, BCC recurrences were only 19% in the PDT plus fractional laser group, compared to 44% for patients receiving PDT alone. Both sets of findings were not statistically significant, however, most likely due to the small size of the study population. Cosmetic outcomes or general ratings for skin appearance were deemed to be “highly satisfying” after both treatments.
The scientists concluded that long-term efficacy appeared to be similar for PDT and fractional laser-PDT, with the latter strategy showing a trend toward a more favorable short-term cure rate. The authors caution that larger clinical trials are needed to enable further refinement and proper substantiation of this approach for the treatment of nodular BCC, as reported online ahead-of-print in the 6 June 2014 British Journal of Dermatology.
Using Cheaper Photosensitizers to Lower Treatment Costs
One of the concerns about using PDT for skin cancer treatment is the potential for increasing medical costs when compared to receiving standard treatments. Typically, this means surgery followed by either chemotherapy or immunotherapy. The idea behind these subsequent treatments is that they can eliminate cancer cells that are not removed by the surgery—mainly because the surgeon can’t see them.
To help curb the cost of PDT, researchers have been interested in identifying cheaper photosensitizing agents. Scientists at Cairo University’s National Institute of Laser Enhanced Sciences in Cairo, Egypt, sought to assess the therapeutic value of using methylene blue, an inexpensive dye that has been used for a variety of medicinal and diagnostic purposes.
A prospective clinical trial was carried out using methylene blue-based PDT in 17 patients suffering from nodular BCC and in three patients with ulcerative BCC. Methylene blue was prepared in two different formulas: a liposomal form for topical use, and an aqueous solution of the dye to be injected directly into the lesion. A treatment session was performed every two weeks until complete response of the lesion, for a maximum of six sessions.
Of the 17 patients who completed the study, 11 patients achieved a complete response with very good cosmetic outcomes and minimal side effects. The researchers concluded that “methylene blue is a cheap promising alternative photosensitizer for PDT of nodular BCC”, as reported online ahead-of-print in the 17 July 2014 issue of Lasers in Medical Science.
Future studies should compare the effects of MAL-PDT to PDT using methylene blue or other photosensitizers. The Natural Health Foundation has supported clinical studies of PDT using Bremachlorin®, another very effective photosensitizing agent and one well worth further investigation in comparative studies of PDT for skin cancers.
Bremachlorin® is available for the treatment of BCC and other skin cancers. Randomized clinical studies for the photodynamic treatment of BCC led to the marketing authorization of this remarkable photosensitizing agent in Russia in 2009. Studies in the Netherlands indicate that this agent is taken up and remains in cancer cells much more effectively when compared to most other photosensitizers.
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Fernández-Guarino M, Harto A, Pérez-García B, Royuela A, Jaén P. Six years of experience in photodynamic therapy for Basal cell carcinoma: results and fluorescence diagnosis from 191 lesions. J Skin Cancer. 2014:849248. Epub 2014 Sep 14.
Haak CS, Togsverd-Bo K, Thaysen-Petersen D, Wulf HC, Paasch U, Anderson RR, Haedersdal M. Fractional laser-mediated photodynamic therapy of high-risk basal cell carcinomas – a randomized clinical trial. Br J Dermatol. 2014 Jun 6. [Epub ahead of print]
Samy NA, Salah MM, Ali MF, Sadek AM. Effect of methylene blue-mediated photodynamic therapy for treatment of basal cell carcinoma. Lasers Med Sci. 2014 Jul 17. [Epub ahead of print]
Leiter U, Eigentler T, Garbe C. Epidemiology of skin cancer. Adv Exp Med Biol. 2014;810:120-40.
Sehgal VN, Chatterjee K, Pandhi D, Khurana A. Basal cell carcinoma: pathophysiology. Skinmed. 2014 May-Jun;12(3):176-81.
Kochneva EV, Filonenko EV, Vakulovskaya EG, Scherbakova EG, Seliverstov OV, Markichev NA, Reshetnickov AV. Photosensitizer Radachlorin®: Skin cancer PDT phase II clinical trials. Photodiagnosis Photodyn Ther. 2010 Dec;7(4):258-67
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