Box-and-whisker plots of area under the receiver operating characteristic curves obtained from prediction models of 12 sets of predictor variables. (a) Training data. (b) Testing data. Char, Predictor variables of tumor characteristics of type, Nottingham score, mitotic count; Char+Rec, Predictor variables of tumor characteristics and receptor status of triple-negative, human epidermal growth factor receptor 2 (HER2), estrogen receptor (ER); tHb, oxyHb, deoxyHb: Predictor variables of pretreatment maximum total hemoglobin (tHb), oxygenated hemoglobin (oxyHb) and deoxygenated hemoglobin (deoxyHb), respectively; tHboxyHb, tHbdeoxyHb: Combined predictor variables of tHb and oxyHb, tHb and deoxyHb, respectively; Char+Rec+corresponding hemoglobin variables: Combined predictor variables of tumor characteristics, receptor status and corresponding hemoglobin predictors. ROC, Receiver operating characteristic.