Field cancerization treatment: Adjustments to an ALA red light photodynamic therapy protocol to improve pain tolerance

Abstract

BackgroundField cancerization (FC) is described as an area with multiple actinic keratosis (AK) in an actinic damaged skin that requires treatment. Photodynamic therapy (PDT) is a treatment option, however, long drug light intervals (DLI) and pain during the illumination remain a challenge ObjectivePain and the efficacy of changes in DLI and illumination during PDT treatment for FC were evaluated MethodsThirty patients with widespread AK of upper limbs were selected. A 20% aminolevulinic acid (ALA) cream was applied on both forearms and hands after a light curettage. Three groups were evaluated: G1 (3 h of DLI); G2 (1.5 h of DLI); and, G3 (1.5 h of DLI with two-minutes pauses every 10 min during illumination). The limbs were treated with a LED prototype at 630 nm (36 J/cm2 of fluence in 40 min of irradiation). The pain score during illumination was evaluated with a numeric scale (from 0 to 10) and pain was defined as low (0–3), moderate (4-6), and severe (7-10). The AK counting was clinically performed before and 30 days after PDT. Significance between groups was tested using ANOVA single factor. ResultsA mean reduction in AK number of 56% in G1, 55% in G2, and 66% in G3 were observed, with no statistical significance. The comparison pain among the groups showed best results for G3 (p < 0,05). ConclusionUsing paused illumination and 1.5 h of DLI was possible to improve tolerance maintaining the clearance in red light ALA - PDT treatment.