REVIEW ARTICLE Radiation dermatitis assessment tools used in breast cancer: A systematic review of measurement properties Tara Behroozian 1 & Lauren T. Milton 1 & Neil H. Shear 2 & Erin McKenzie 1 & Yasmeen Razvi 1 & Irene Karam 1 & Kucy Pon 2 & Henry Lam 1 & Emily Lam 1 & Edward Chow 1 Received: 16 July 2020 /Accepted: 9 November 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract Purpose This review aimed to assess the quality and efficacy of tools currently used in breast cancer patients to score radiation dermatitis (RD), a common debilitating side effect of radiotherapy (RT). Methods A search was conducted through Ovid Medline, Embase, and Cochrane Central Register of Controlled Trials databases on 14 February 2020. English articles that evaluated an instrument’s use in assessing RD among breast cancer patients receiving external beam RT were included. Studies that reported on the reliability, validity, or concordance of items between assessment tools were included in accordance with the Consensus-Based Standards for the Selection of Health Measurement Instruments (COSMIN) criteria. Results Twelve studies were included in this review, with a total of 13 skin toxicity assessment tools discussed. Tools that assessed clinician-reported outcomes (CROs) mostly reported moderate correlation with biophysical parameter (BP) measure- ments and low correlation with patient-reported outcomes (PROs). Traditionally used CRO scoring tools demonstrated moderate inter-rater reliability between clinicians, likely due to the subjective nature of items on the grading scales. Most commonly used tools were found to be either insufficient or indeterminate in their measurement properties. Conclusions Current standardized tools that measure CROs are subject to clinician interpretation and fail to represent the patient experience. Tools designed to assess PROs are promising in their assessments of the impact of RT on patient quality of life; however, most PRO tools are generic to all skin conditions and require further validation for use in breast cancer. Among tools that measure CROs, PROs, and BPs, there is insufficient evidence on their measurement properties to establish a “gold standard” for the assessment of RD in breast cancer patients. Keywords Breast cancer . Radiotherapy . Radiation dermatitis . Skin toxicity . Assessment tool . Skin grading scale Introduction Despite the proven benefit of adjuvant radiotherapy (RT) in pro- moting loco-regional control amongst non-metastatic breast can- cer patients, approximately 97.3% of patients experience acute skin reactions, known as radiation dermatitis (RD), both during and in the weeks following RT [ 1, 2]. RD exists in progressive states of severity, from erythema to desquamation; in some cases, moist desquamation can result in poor cosmetic outcomes, treat- ment interruptions, and diminished quality of life (QOL) [3, 4]. Late skin reactions (i.e. fibrosis, telangiectasia, atrophy), which develop in the months to years following treatment, may cause further complications and hinder the reconstructive process in post-mastectomy patients [2, 5]. While there is a high prevalence of RD amongst patients undergoing breast RT, there is limited consensus across institu- tions on how to adequately assess symptoms due to high varia- tion and lack of standardization between instruments [6]. Most assessment tools that have been implemented in clinical practice include surveys to assess clinician-reported outcomes (CROs) and/or patient-reported outcomes (PROs) to score observable skin toxicities and individual, subjective symptoms, respectively [7, 8]. A review by Baines et al. found standardized CRO tools to be inconsistent and insufficient in capturing patients ’ symptoms * Edward Chow Edward.Chow@sunnybrook.ca 1 Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada 2 Division of Dermatology, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada Supportive Care in Cancer https://doi.org/10.1007/s00520-020-05889-w