Impact of positive positron emission tomography on prediction of freedom from progression after Stanford V chemotherapy in Hodgkin's disease

Purpose To correlate [F-18] fluorodeoxyglucose positron emission tomography ([F-18] FDG- PET) status after chemotherapy, but before radiation, with outcome in patients treated with the Stanford V regimen. Patients and Methods We analyzed retrospectively 81 patients with Hodgkin's disease who had serial [F-18] FDG- PET scans performed at baseline and again at the completion of Stanford V chemotherapy, before planned radiotherapy. Patients with favorable stage I/II ( nonbulky mediastinal disease) and those with bulky mediastinal disease or stage III/IV were scanned after 8 and 12 weeks of chemotherapy, respectively. Radiotherapy fields were determined before starting chemotherapy based on baseline computed tomography scans. Results After chemotherapy, six of 81 patients had residual [F-18] FDG-PET-positive sites, all in sites for which radiotherapy was planned. Four of the six patients with positive [F-18] FDG- PET scans after chemotherapy experienced relapse compared with just three of 75 patients with negative [F-18] FDG-PET scans. At a median follow- up of 4 years, the freedom from progression ( FFP) was 96% in postchemotherapy [F-18] FDG-PET-negative patients versus 33% in [F-18] FDG-PET-positive patients ( P =.0003). In a bivariate Cox model, [F-18] FDG-PET positivity after chemotherapy remained a highly significant predictor of progression- free survival even after controlling for bulky disease and International Prognostic Score more than 2. Conclusion These data indicate that PET status after chemotherapy is strongly predictive of FFP with the Stanford V regimen despite the use of consolidative radiotherapy. These results have implications for the design of clinical trials adapted to functional imaging.