Although IF is traditionally considered the gold standard for determining expression alterations in γ-H2AX and 53BP1 [17,18], our study, using archival GIST samples, clearly demonstrated robust and positive correlations between the expression percentages given by IF and H-scores given by IHC for both γ-H2AX and 53BP1. The gene discussed is TP53BP1; the disease is gastrointestinal stromal tumor.