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

Background: Field 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 OBJECTIVE: Pain and the efficacy of changes in DLI and illumination during PDT treatment for FC were evaluated METHODS: Thirty 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/cm 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.

Results: A 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).

Conclusion: Using paused illumination and 1.5 h of DLI was possible to improve tolerance maintaining the clearance in red light ALA - PDT treatment.