Kaplan-Meier curve showing FFS. FFSs are according to the combined use of the clinical risk score and the FDG-PET response in 78 patients with recurring NHL (A), 23 patients with recurring HL (B), and the total of 101 patients with recurring lymphoma (C). Four different categories of combined risk score (CRS) could be distinguished by the combined use of the clinical risk score and the FDG-PET response. The combined risk score is calculated by the sum of the clinical risk score (CliRS 0-3) and the PET response score (0-2).