Dose-surface analysis for prediction of severe acute radio-induced skin toxicity in breast cancer patients

• Published in: Acta oncologica 2016-01, Vol.55 (4), p.466-473
• Main Authors: Pastore, Francesco, Conson, Manuel, D'Avino, Vittoria, Palma, Giuseppe, Liuzzi, Raffaele, Solla, Raffaele, Farella, Antonio, Salvatore, Marco, Cella, Laura, Pacelli, Roberto
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Breast Neoplasms - radiotherapy; Breast Neoplasms - surgery; Dose-Response Relationship, Radiation; Female; Humans; Mastectomy, Segmental; Middle Aged; Models, Biological; Multivariate Analysis; Prospective Studies; Radiation Injuries - etiology; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted - methods; Radiotherapy, Conformal - adverse effects; Skin - radiation effects
• ISSN: 0284-186X; 1651-226X
• DOI: 10.3109/0284186X.2015.1110253

Severe acute radiation-induced skin toxicity (RIST) after breast irradiation is a side effect impacting the quality of life in breast cancer (BC) patients. The aim of the present study was to develop normal tissue complication probability (NTCP) models of severe acute RIST in BC patients. We evaluated 140 consecutive BC patients undergoing conventional three-dimensional conformal radiotherapy (3D-CRT) after breast conserving surgery in a prospective study assessing acute RIST. The acute RIST was classified according to the RTOG scoring system. Dose-surface histograms (DSHs) of the body structure in the breast region were extracted as representative of skin irradiation. Patient, disease, and treatment-related characteristics were analyzed along with DSHs. NTCP modeling by Lyman-Kutcher-Burman (LKB) and by multivariate logistic regression using bootstrap resampling techniques was performed. Models were evaluated by Spearman's Rs coefficient and ROC area. By the end of radiotherapy, 139 (99%) patients developed any degree of acute RIST. G3 RIST was found in 11 of 140 (8%) patients. Mild-moderate (G1-G2) RIST was still present at 40 days after treatment in six (4%) patients. Using DSHs for LKB modeling of acute RIST severity (RTOG G3 vs. G0-2), parameter estimates were TD50=39 Gy, n=0.38 and m=0.14 [Rs = 0.25, area under the curve (AUC) = 0.77, p = 0.003]. On multivariate analysis, the most predictive model of acute RIST severity was a two-variable model including the skin receiving ≥30 Gy (S30) and psoriasis [Rs = 0.32, AUC = 0.84, p