The impact of different fluence rates on pain and clinical outcome in patients with actinic keratoses treated with photodynamic therapy

Abstract

According to our observations a fluence rate between 25 and 50 mW/cm2 is effective and better tolerated by patients treated with topical 5-ALA PDT for AKs.

A controlled trial of photodynamic therapy of actinic keratosis comparing different red light sources

“…It is not clear how far different red light sources result in different efficacy rates and pain scores. It has been reported that a higher fluence rate of the light source caused higher pain sensations [23]. However, in our study, the fluence rate (= irradiance, 196 mW/cm 2 ) of the broad-band VIS + wIRA light source, which caused significantly less pain during PDT but had comparable efficacy rates, was even higher than the irradiance with the incoherent halogen lamp (150 mW/cm 2 ).…”

Red light photodynamic therapy for actinic keratosis using 37 J/cm2: Fractionated irradiation with 12.3 mW/cm2 after 30 minutes incubation time compared to standard continuous irradiation with 75 mW/cm2 after 3 hours incubation time using a mathematical modeling

“…The continuous 75 mW/cm 2 red light protocol was considered due to its standardized use across Europe while the choice of the fractionated 12.3 mW/cm 2 red light protocol was motivated by the FLEXITHERALIGHT Project (http://www.flexitheralight.com/). This French National Research Agency Project focuses on the development of a biophotonic device based on a flexible light emitting textile enabling a fractionated irradiation with a 12.3 mW/cm 2 fluence rate for the PDT treatment of actinic keratosis.…”

The interpretation of clinical studies on the photodynamic treatment of actinic keratosis

“…Dirschka et al [5] however, not only failed to discuss reasons for the differences between the narrow-band and broad-band types of sources used, but also did not comment on the differences found between the various types of broad-band sources employed. Additionally, despite the findings of von Felbert et al [2] who found the use of a broad-band source with water filter to be associated with less pain than that caused by a narrow-band source, and a study by Apalla et al [6] who found the use of a broad-band source without a water filter to be associated with pain, Dirschka and colleagues did not consider the fact that broad-band sources would result in absorption over a broader spectral range (and possibly encompassing several maxima) of the photosensitizer as has been discussed previously [7]. Additionally, previous studies in which no differences were found between narrow- and broad-band sources [1], [8], [9] were not considered.…”

“…Possible reasons for such a pronounced difference between the response rates in these two studies were however not discussed by Dirschka and colleagues [5]. While the extent of pain experienced during photodynamic therapy (which is deemed to be the main side-effect of PDT [6], [7]) was documented by Dirschka et al [5], possible reasons for the greater incidence of pain during the use of the narrow-band sources were not considered. In the Dirschka et al study, a comparison of the photosensitizers used showed BF-200 ALA to be superior to MAL, but again, a study with contradictory findings (Gholam et al [3]) is not discussed.…”