Chronological Skin Changes Through Postmastectomy Radiotherapy Based on Radiotherapy Techniques: Using Quantitative Dermatological Measurements

Abstract

<b><i>Background:</i></b> There has been few research on how to measure skin status quantitatively throughout the course of radiotherapy (RT). We evaluated the changes in the skin induced by 2 different RT techniques using objective measurements in breast cancer patients. <b><i>Methods:</i></b> In this prospective study, between August 2015 and March 2019, serial measurements of the dermatological factors during and after postmastectomy radiotherapy (PMRT) were made in 40 breast cancer patients. PMRT was performed using the conventional photon tangential technique (PTT) or patient-tailored bolus technique (PTB). We analyzed these measurements using a mixed effect model and compared the clinically evaluated radiation dermatitis and patient-reported outcomes (PROs). <b><i>Results:</i></b> The trend of changes in melanin and erythema was significantly different between the PTB and PTT groups (<i>p</i> = 0.045 and 0.016, respectively). At the 3-month follow-up erythema intensity and melanin were higher in the PTB group than in PTT group (both <i>p</i> &#x3c; 0.001). Eight patients (40% in the PTB group) reported grade 2 radiation dermatitis and 1 patient (5% in the PTB group) reported grade 3 radiation dermatitis. No grade 2 or higher radiation dermatitis was found in the PTT group. Ten patients (50%) in the PTB group and 3 patients (15%) in the PTT group reported severe erythema likely due to questionable clinical evaluation, but hyperpigmentation was rarely reported at the follow-up visits. <b><i>Conclusion:</i></b> The PTB group showed higher intensity of erythema at the end of RT than the PTT group and the increase in melanin lasted until the 3-month follow-up visits in the PTB group. Moreover, patients subjectively appealed more severe symptoms following PTB in PROs.