Development of a new photonumeric scale for acute radiation dermatitis in patients with breast cancer.

Abstract

86 Background: The Common Terminology Criteria for Adverse Events (CTCAE) is frequently used to grade the severity of acute radiation dermatitis (ARD), but has not been validated despite decades of clinical use. We sought to develop a photonumeric scale to consistently describe ARD in breast cancer patients undergoing radiation (RT). Methods: Patients enrolled on a prospective study that included photographs and quantitative measurements of erythema and hyperpigmentation using colorimetry. 209 photographs from 35 patients with white skin and 369 photographs from 50 patients with skin of color were used to develop two photonumeric scales. Predominant erythema (in white skin) OR hyperpigmentation (in skin of color) were rated on a 4 point scale, with grading of desquamation on a separate 3 point scale. Four raters used both CTCAE and photonumeric scales to independently score all photographs. Intra- and inter-rater agreements were assessed using weighted kappa scores. Results: Using the CTCAE, 95% of photos were rated as grade 1 or 2. There was a trend toward higher grade in patients with skin of color, with grade 2 toxicity in 43% vs. 24%. Intra-rater agreement for CTCAE ratings was 65—87% (kappa 0.34—0.67), with a wide range of inter-rater agreement (56—81% agreement fraction, kappa 0.04—0.58). Using the photonumeric scale, intra-rater agreement was high for erythema/hyperpigmentation in patients with white skin (74—82%, kappa 0.49—0.70) and skin of color (69—86%, kappa 0.55—0.79), along with desquamation (78—87%, kappa 0.52—0.66). There was moderate inter-rater agreement for erythema/hyperpigmentation (51—82%, kappa 0.15—0.71) and desquamation (63—88%, kappa 0.36—0.58). Colorimetric measurements correlated strongly with photonumeric grade. Conclusions: We report a new photonumeric scale for ARD in breast cancer patients with satisfactory reliability across the spectrum of skin pigmentation. Intra-physician ratings were consistent, with moderate inter-physician agreement. The CTCAE functions as a binary scale, with 95% of ARD rated as grade 1 or 2 toxicity. Future work includes correlation with patient-reported outcomes and physician ratings at the point-of-care. Funded by a Munn Idea Grant (G011480).