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

Abstract

Purpose: To correlate [(18)F]fluorodeoxyglucose positron emission tomography ([(18)F]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 [(18)F]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 [(18)F]FDG-PET-positive sites, all in sites for which radiotherapy was planned. Four of the six patients with positive [(18)F]FDG-PET scans after chemotherapy experienced relapse compared with just three of 75 patients with negative [(18)F]FDG-PET scans. At a median follow-up of 4 years, the freedom from progression (FFP) was 96% in postchemotherapy [(18)F]FDG-PET-negative patients versus 33% in [(18)F]FDG-PET-positive patients (P < .0003). In a bivariate Cox model, [(18)F]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.