Meta-analysis of chemotherapy versus combined modality treatment trials in Hodgkin's disease. International Database on Hodgkin's Disease Overview Study Group

Abstract

Design: To perform a meta-analysis of all randomized trials that compared chemotherapy (CT) alone versus combined modality treatment (CT + radiotherapy [RT]) for which individual patient data could be made available.

Patients and methods: Data on 1,740 patients treated on 14 different trials that included 16 relevant comparisons have been analysed. Eight comparisons were designed to evaluate the benefit of additional RT after the same CT (CT1 v CT1 + RT; additional RT design). Eight comparisons were designed to evaluate whether RT in a combined modality setting can be substituted by CT using either more cycles of the same CT or regimens that contain additional drugs (CT1 + CT2 v CT1 + RT or CT1 v CT2 + RT; parallel RT/CT design).

Results: Additional RT showed an 11% overall improvement in tumor control rate after 10 years (P = .0001; 95% confidence interval [CI], 4% to 18%). No difference could be detected with respect to overall survival (P = .57; 95% CI, -10% to 4%). In contrast, when combined modality treatment was compared with CT alone in the parallel-design trials, no difference could be detected in tumor control rates (P = .43; 95% CI, -6% to 9%), but overall survival was significantly better after 10 years in the group that did not receive RT (P = .045; 8% difference; 95% CI, 1% to 15%). There were significantly fewer fatal events among patients in continuous complete remission (relative risk [RR], 1.73; 95% CI, 1.17 to 2.53; P = .005) if no RT was given.

Conclusion: Combined modality treatment in patients with advanced-stage Hodgkin's disease overall has a significantly inferior long-term survival outcome than CT alone if CT is given over an appropriate number of cycles. The role of RT in this setting is limited to specific indications.