Preliminary reliability and validity testing of a new Skin Toxicity Assessment Tool (STAT) in breast cancer patients undergoing radiotherapy

Clear consensus on the clinical evaluation of acute skin toxicity among cancer patients undergoing radical radiotherapy (RT) is currently lacking. This study investigates the reliability and validity of a new Skin Toxicity Assessment Tool (STAT) to evaluate the objective and subjective manifestations of RT-induced acute skin effects. The STAT was designed by a multidisciplinary team involved in the management of radiation skin reactions. The tool has 3 components: patient and treatment parameters, observer scoring, and patient-reported symptoms, and was piloted in a cohort of 27 breast cancer patients by pairs of independent blinded observers. Each patient was assessed weekly during RT and 2 weeks after therapy completion. Validity and reliability testing of the STAT was performed. Information on the tool's ease of use was obtained by recording the time necessary to complete the assessment at each visit and by a survey among the tool's users. All subjects developed some degree of skin reaction during breast RT. The level of agreement between observers in eliciting subjective complaints ranged from 72% to 92% (95% CI = 63-96%; kappa = 0.33-0.68). The interobserver agreement in scoring skin reactions ranged from 65.0 to 97.5% (kappa = 0.46-0.81). Objective and subjective toxicity scores were significantly correlated (P < 0.05). The STAT was easy to use and required on average a few minutes to complete at each visit. The STAT is an easy-to-use, standardized instrument to evaluate acute skin reaction and may be applied to clinical care and research in patients undergoing radiotherapy.