120 Chapter 7 Table 1. Scoring methods used to predict response to chemoradiotherapy on baseline MRI Response method Score 5-point confidence score (van Griethuysen et al.)* 1 = High risk - Highly unlikely to achieve (near-)complete response (7 high risk criteria)* 2 = Moderately high risk - Unlikely to achieve (near-)complete response (≥5 high risk criteria)* 3 = Intermediate risk - Equivocal (Not meeting the criteria for scores 1–2 or 4–5) 4 = Moderately low risk - Likely to achieve (near-)complete response (≥3 low risk criteria)* 5 = Low risk - Highly likely to achieve (near-)complete response (≥5 low risk criteria)* 4-point risk score (see Figure 1) 1 point for each of the following high-risk features (total score 0-4): · Obvious macroscopic MRF invasion# · High risk T-stage (bulky, T3c-4)# · Obvious nodal involvement# · Obvious EMVI# Dichotomized (2-point) risk score (see Figure 2) 0 = Likely to reach good or complete response: Small semicircular or polypoid tumors Free MRF (or possibly borderline MRF involvement) T1-2 or early stage T3 (T3ab) 1 = Unlikely to reach good or complete response: Bulky semicircular or circular tumors High risk (T3cd or T4) T-stage With or without MRF involvement * The confidence score of van Griethuysen is a composite score that combines T-stage, size, signal (heterogeneous/ homogeneous), shape (regular/irregular), N-stage, EMVI, and MRF involvement as assessed on T2-weighted MRI. High risk criteria include ≥T3cd stage, tumor size > 5 cm, heterogeneous tumor signal, irregular tumor shape, N+ stage, EMVI+, and MRF+. Low risk criteria include ≤T3ab stage, tumor size < 3 cm, homogeneous tumor signal, regular tumor shape, N0 stage, EMVI- and MRF-. Readers were provided with the originally published paper and scoring definitions while performing their scorings [17]. # Readers were instructed to only indicate ‘yes’ if they were confident that a respective high-risk feature was present. When in doubt, they were instructed to select ‘no’.
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