MRC TE18 / EORTC 30942
After orchidectomy for stage I seminoma, can adjuvant radiotherapy be safely reduced from 30 Gy in 15 fractions to 20 Gy in 10 fractions?
Relapse control was essentially unchanged
At median follow-up of 61 months, there were 11 relapses with 20 Gy versus 10 with 30 Gy. The reported absolute difference in 2-year relapse rates was 0.7 percentage points. The hazard ratio for relapse was 1.11 (90% CI 0.54–2.28). The trial was powered to exclude an absolute increase in 2-year relapse of approximately 3–4 percentage points.
NNT/NNH: Not applicable. This was a non-inferiority dose-de-escalation comparison rather than a superiority trial.
Less acute morbidity with 20 Gy
Four weeks after starting treatment, moderate/severe lethargy was reported by 5% with 20 Gy versus 20% with 30 Gy. Inability to carry out normal work was reported by 28% versus 46%. By 12 weeks these differences had largely resolved.
Non-inferiority supported: HR for relapse 1.11 (90% CI 0.54–2.28). The upper confidence limit remained below the prespecified clinically important threshold for excess relapse used in the trial design.
Reducing adjuvant seminoma radiotherapy from 30 Gy/15 fractions to 20 Gy/10 fractions substantially reduces short-term treatment burden without a clinically important increase in relapse at the studied follow-up. This is a dose-de-escalation result: the evidence supports using less treatment with similar disease control, rather than demonstrating that 20 Gy is superior to 30 Gy.
The trial was designed around relapse rather than overall survival, which is difficult to improve in a disease with very high salvageability. Long-term risks such as second malignancy require longer follow-up than the primary report. The evidence applies to appropriately staged stage I seminoma treated after orchidectomy.
- Jones WG, Fossa SD, Mead GM, et al. J Clin Oncol. 2005;23:1200–1208.
- PubMed: PMID 15718317
- Journal of Clinical Oncology
- EORTC study record