Response to the Comment on "Photobiomodulation therapy for the prevention of acute radiation dermatitis (RD) in head and neck cancer patients (DERMISHEAD trial)" by Baiocchi et al

Abstract

Response to the Comment on ''Photobio-modulation therapy for the prevention of acute radiation dermatitis (RD) in head and neck cancer patients (DERMISHEAD trial)" by Baiocchi et al To the Editor We want to thank Baiocchi et al. for the letter [1], allowing us to clarify some methodological issues of our paper [2]. At the Limburg Oncologic Laser Institute (LOwLIght), we have already extensive experience in investigating the use of photo-biomodulation therapy (PBMT) for the prevention and management of acute radiodermatitis (ARD) in cancer patients [3-6]. In addition, Robijns et al. recently published a narrative review on the use of PBM for ARD [7]. The review shows that PBMT could significantly reduce ARD severity, but the current data is too limited to make definitive conclusions. The DERMISHEAD trial described in this paper is the first patient-blinded randomized controlled trial (RCT) in head and neck (HNC) cancer patients studying the effectiveness of PBMT in the prevention and management of ARD [2]. In this trial, the operator used a PBM handheld device 5 cm above the treatment area. Before the application, the operator set the emission mode, frequency, time and intensity values, and the extent of the area to be treated. The device calculated and displayed the energy density to be supplied with the current settings. The handheld device was used in a scanning motion over the treatment area by the operator. The PBM device was yearly checked and calibrated by a service engineer. The exact skin dose delivered with the PBM device was not recorded for this trial due to the unavailability of measurement equipment. In ideal circumstances, light measurements should occur before, during, and after the trial to ensure that the intended parameters are applied. Spectrometers could be used to analyse spectral characteristics (i.e., light intensity, polarization) of laser light at a specific wavelength. Further, an optical power meter can be used to measure the power (W) and irradiance (W/cm 2) based on the size of the sensor or beam area values, but they do not provide spectral information. A more reliable method to measure light and irradiance's spatial distribution is via thermopiles or beam profilers [8,9]. When PBM is applied in direct contact with the skin, the dose delivery will be more controlled. In our case, this was not possible due to hygiene measures and increased risk of infection when the device is in direct contact with the irradiated, often fragile, wounded skin. However, some PBM devices on the market make direct skin-to-skin contact possible due to the use of single-use disposable sleeves [10]. In conclusion, further research is needed to make hard conclusions regarding PBM and ARD. Future studies should incorporate a double-blind RCT design with a larger patient population, well-described and complete PBMT parameters, and a longer follow-up time.