Evaluating the safety and efficacy of aminolevulinic acid 20% topical solution activated by blue light in the treatment of facial cutaneous squamous cell carcinoma in situ

Abstract

Background: Cutaneous squamous cell carcinoma in situ (isSCC) is a common skin cancer occurring from sun exposure and often appears on the face.  Treatment is primarily surgical but less invasive treatments are desirable. Currently, aminolevulinic acid for photodynamic therapy (ALA-PDT) is approved in the US and Canada for the treatment of single and multiple non-hyperkeratotic actinic keratoses of the face and scalp. This study evaluated the safety, tolerability, and efficacy of ALA-PDT for treatment of facial isSCC.

Methods: Thirty-two patients with biopsy-confirmed isSCC on the face were recruited. Lesions 0.4–1.3 cm in diameter were included. Per the actinic keratosis treatment protocol, the lesion was debrided with a 4 x 4 gauze and ALA 20% topical solution was applied to the lesion and adjacent skin and incubated for 18–24 hours, followed by blue light therapy 16 minutes 40 seconds at 10 J/cm2. Patients underwent two treatments with ALA-PDT spaced 28 +/- 3 days apart. The area of the original lesion was excised eight weeks following the second treatment for histopathological assessment. The primary efficacy endpoint was the complete absence histologically of the isSCC at end of treatment. The secondary efficacy endpoint was the achievement of clinical clearance of the skin lesion. Safety assessment was done through adverse events and local skin reactions (LSRs; erythema, flaking/scaling, crusting, swelling, vesiculation/pustulation, and erosion/ulceration) and site pain within 15 minutes of each treatment session.

Results: Of the 32 patients enrolled, two did not complete the study. No residual SCCis was detected in 30/30 (100%) patients. Clinical clearance was achieved in 30/30 (100%) of the patients by the end of treatment. None of the patients experienced related adverse events and only 2/30 (5%) experienced an AE of hypertension and was considered to be unrelated. The most common LSRs were erythema and scaling and were primarily mild, seen to occur immediately after both treatments and diminished over time. The average median ± SD immediate post-treatment pain score was 2.56 ± 2.15 on the VAS scale.

Conclusion: The ALA-PDT protocol outlined in this study appears to be a very effective, safe and well-tolerated treatment option for isSCC on the face.