Photodynamic therapy uses broaden as more data emerges
Miami Beach, Fla. — Physicians have greatly changed the ways in which they use photodynamic therapy (PDT) since it was introduced, according to an expert who spoke at the South Beach Symposium recently.
Since earning Food and Drug Administration (FDA) approval in 1999, PDT with aminolevulinic acid (ALA) has evolved to encompass off-label uses including treatment of actinic keratoses (AKs) on the hands and arms, superficial nonmelanoma skin cancers in nonsurgical candidates and actinic cheilitis (AC), says Joel L. Cohen, M.D., director of AboutSkin Dermatology in Englewood and Lone Tree, Colo., and associate clinical professor at the University of Colorado department of dermatology.
“People are using phototherapy in many new and exciting ways. In my practice, I use PDT from a medical, surgical and cosmetic perspective,” he says.
Although the FDA approved PDT for application to specific areas, Dr. Cohen says, “Broad application is now pretty standard.”
Similarly, methods for enhancing ALA penetration on the extremities include vigorous preparation of the skin, sometimes including application of topical retinoids such as tazarotene. In this regard, a 10-patient study showed that pretreatment with tazarotene gel 0.1 percent twice daily for one week before ALA PDT with blue light resulted in a statistically significant decline in lesion counts versus baseline eight weeks post-treatment (p=0.0002; Galitzer BI. J Drugs Dermatol. 2011;10(10):1124-1132).
Other methods to enhance ALA penetration on the arms and hands include the addition of occlusion and heat during the incubation period, Dr. Cohen says. In Europe, he adds, physicians commonly use PDT (albeit usually a different formulation no longer available in the United States — Metvix; methyl aminolevulinate, Galderma) for very superficial basal cell carcinoma (BCC; Matei C, Tampa M, Poteca T, et al. J Med Life. 2013;6(1):50-54) and squamous cell carcinoma (SCC) in situ.
Dr. Cohen says he often uses PDT for patients with superficial nonmelanoma skin cancers (NMSC) who are poor surgical candidates due to age or other reasons (inability to care for a wound, or patient on chemotherapy). For example, “Such a patient may specifically have SCC in situ. If the base of the biopsy specimen is visualized, and there’s no concern about any invasive component and no evidence of significant follicular extension, I may use PDT,” he says.
Such cases require disclosing to the patient and/or patient’s family that the treatment is not FDA-approved for this indication, but it may be appropriate in the case at hand, he says.
“In some cases, we’ll gently scrape the skin with a curette to create a minor abrasion to enhance topical penetration if the lesion is a bit keratotic, then apply the Levulan (DUSA Pharmaceuticals) ALA under occlusion (using Saran Wrap, S.C. Johnson & Son; or Glad Press’n Seal, Glad Products). Usually with a couple treatments, one will see a response. And that may be preferable because the patient can go back to a nursing home without any woundcare requirements,” Dr. Cohen says. “This would not be the case if the patient had undergone electrodesiccation and curettage, as this treatment would necessitate at least some woundcare.”