Relationship between ZAP-70 and IGHV mutation status in defining the time from diagnosis to initial therapy. Kaplan-Meier curves depict the proportion of untreated patients with CLL according to the time since diagnosis. The symbols represent the time at which patients were censored. The patients were divided into 4 subgroups according to their ZAP-70 expression and IGHV mutation status. The legend is provided in each panel for these 4 subgroups, namely cases that were ZAP-70 negative and that used M-IGHV (ZAP-70⁻/M-VH; ■), cases that were ZAP-70–negative but used U-IGHV (ZAP-70⁻/U-VH; ▴), cases that were ZAP-70–positive but used M-IGHV (ZAP-70⁺/M-VH; ▾), and cases that were ZAP-70–positive and used U-IGHV (ZAP-70⁺/U-VH; ♦). The median time from diagnosis to initial therapy for subgroup is listed in parentheses in the legend. The number of patients in each subgroup is provided in the legend. Panel A provides data for the entire validation cohort of 705 patients. Panel B provides data for the 521 patients in the validation cohort who contributed samples for analyses prior to receiving therapy for CLL. Panel C provides data for the 199 patients who presented with early-to-intermediate stage disease within 1 year of diagnosis prior to receiving therapy for CLL. Panel D provides data for the 323 patients who had cytogenetic analyses performed on their leukemia cells at the time of sample collection (Table 1).