Single treatment of non-melanoma skin cancers using a pulsed-dye laser with stacked pulses

Abstract

Background and objective: Non-melanoma skin cancers are the most common cause of cancer worldwide. Within this grouping, the most common skin cancer is basal cell carcinoma (BCC) followed by squamous cell carcinoma (SCC). Recent evidence has shown that BCCs can be cleared by a pulsed-dye laser after multiple treatments using a single pass setting. Given the necessity for multiple treatments in the prior studies, we sought to determine whether tumor clearance could instead be achieved using a single treatment of the pulsed-dye laser in a stacked pulse setting.

Study design/materials and methods: Twenty patients with 23 biopsy-proven BCCs and SCCIS that measured 0.4-3 cm in size and located on the trunk and extremities were recruited for this study. The lesions were randomized into three study arms: a control group (no treatment), first treatment group (S1), and second treatment group (S2). The S1 group was treated using a 595 nM pulsed-dye laser (PDL) at pulse energy of 15 J/cm(2), 3-millisecond pulse length, with no dynamic cooling, using a 7-mm spot size with 10% overlap of pulses and two passes. The S2 group was treated using the same 595 nM PDL at 7.5 J/cm(2), 3-millisecond pulse length, with no dynamic cooling, using a 10-mm spot size with 10% overlap of pulses and double stacked pulses. All the treated lesions were treated with a 4 mm margin of clinically normal skin. The lesions were subsequently surgically excised and examined by histopathology.

Results: There was no significant difference in the dimensions of the tumors between the three study arms, with a mean area of 94 mm(2) [SEM ± 15.2] for the control group, 88 mm(2) [SEM ± 12.1] for the S1 treatment group, and 105 mm(2) [SEM ± 23.6] for the S2 treatment group. In the control group, there were two out seven lesions with no residual tumors, representing a background tumor clearance rate of approximately 28%. The S1 treatment group had two out of eight lesions with no residual lesion representing a clearance rate of 25%, similar to the background clearance rate. The S2 treatment group had a clearance rate of five out seven lesions, representing a clearance rate of 71%. The two lesions with residual tumors were noted to be beyond the central treatment zone by histopathology and if excluded, results in a clearance rate of 100%. By the Fisher's exact test with a Bonferroni correction, there is a trend towards significance between the S2 treatment group and the control group with a P-value of 0.028.

Conclusions: The results of our pilot study suggest that BCCs and SCCIS can be cleared in a single treatment using a pulsed-laser in a stacked pulse setting. However, given the small sample size of this pilot study, further larger scale studies will be needed to determine statistical significance and long-term recurrence rate and to further validate these findings.