de Haas 2007.

Methods	D: This was a single‐centre, randomised, comparative study. The study sequentially recruited participants attending the department RS: Patches of Bowen's disease were randomised, but the paper provided no method of randomisation AC: This was unclear B: This was unclear
Participants	Netherlands: 40 participants (17 men and 23 women with 50 biopsy‐proven lesions of Bowen's disease) Mean treated lesion diameter = 14.5 mm (range = 5 to 40 mm) Mean age = 74 years (49 to 91 years)
Interventions	For both groups, surface scales and rusts were removed before the application of topical aminolevulinic acid (ALA). Topical ALA was left in place for 4 hours, with a margin of 1 cm T1: ALA‐PDT ‐ Bowen's patches illuminated 4 hours after ALA application with 75 J cm‐² (single illumination) T2: ALA‐PDT ‐ Bowen's patches illuminated at 4 and 6 hours after ALA application with 20 and 80 J cm‐², respectively, separated by a 2‐hour dark interval (2‐fold illumination group)
Outcomes	The lesion was the unit of analysis ‐ all sites included Primary clinical response (measured at 4 weeks and 3‐monthly to 2 years). (Complete response was defined as no clinical evidence of disease, with macroscopically normal skin at the treated site) Cosmesis was scored at 12 months
Notes	Each illumination was delivered at 50 mWcm‐². A diode laser and light‐emitting diode provided illumination at a wavelength of 630 nm Intervention product information/details ALA ointment 20% (FLUKA, Zwijndrecht, the Netherlands) in Instillagel® (Medeco, Oud Beijerland, the Netherlands)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	The paper did not describe the method of randomisation
Allocation concealment (selection bias)	Unclear risk	The paper gave no details
Incomplete outcome data (attrition bias) All outcomes	Low risk	There was no loss to follow up
Blinding participants	Unclear risk	There was no evidence of blinding
Blinding clinicians	Unclear risk	There was no evidence of blinding
Blinding pathologist	Unclear risk	There was no mention of a pathologist
Blinding outcome assessor	Unclear risk	There was no evidence of blinding
Baseline comparability	Unclear risk	The paper gave no details about baseline characteristics of lesions