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

<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> &lt; 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.

**背景：** 目前针对放射治疗（Radiotherapy, RT）全程皮肤状态的定量评估方法的相关研究较为匮乏。本研究针对乳腺癌患者，采用客观检测手段，评估两种不同放射治疗技术所诱导的皮肤损伤变化。**方法：** 本研究为前瞻性研究，纳入2015年8月至2019年3月期间的40例乳腺癌患者，对其接受乳房切除术后放射治疗（Postmastectomy Radiotherapy, PMRT）期间及术后的皮肤学指标进行系列检测。所有患者的PMRT分别采用常规光子切线野技术（Conventional Photon Tangential Technique, PTT）或患者个体化推量技术（Patient-tailored Bolus Technique, PTB）实施。本研究采用混合效应模型对检测数据进行分析，并对比临床评估的放射性皮炎与患者报告结局（Patient-reported Outcomes, PROs）。**结果：** PTB组与PTT组的黑色素、红斑变化趋势存在显著差异（分别对应p=0.045与p=0.016）。术后3个月随访时，PTB组的红斑强度与黑色素水平均高于PTT组（均p<0.001）。PTB组共有8例患者（占比40%）报告出现2级放射性皮炎，PTT组有1例患者（占比5%）报告出现3级放射性皮炎；PTT组未出现2级及以上放射性皮炎病例。PTB组有10例患者（占比50%）、PTT组有3例患者（占比15%）报告存在重度红斑，该结果可能受临床评估准确性的影响；但随访期间极少有患者报告色素沉着过度。**结论：** 相较于PTT组，PTB组在放射治疗结束时的红斑强度更高，且PTB组的黑色素水平升高可持续至术后3个月随访时。此外，通过患者报告结局可知，接受PTB治疗的患者主观报告的症状更为严重。