Randomized trial of 30 versus 20 Gy in the adjuvant treatment of stage I testicular seminoma: A report on medical research council trial TE18, European Organisation for the Research and Treatment of Cancer Trial 30942 (ISRCTN18525328)

Purpose To assess the possibility of reducing radiotherapy doses without compromising efficacy in the management of patients with stage I seminoma. Patients and Methods Patients were randomly assigned 20 Gy/10 fractions over 2 weeks or 30 Gy/15 fractions during 3 weeks after orchidectomy. They completed a symptom diary card during treatment and quality-of-life forms pre- and post-treatment. The trial was powered to exclude absolute differences in 2-year relapse rates of 3% to 4% (alpha =.05 [one sided]; 90% power). Results From 1995 to 1998, 625 patients were randomly assigned to treatment. Four weeks after starting radiotherapy, significantly more patients receiving 30 Gy reported moderate or severe lethargy (20% v 5%) and an inability to carry out their normal work (46% v 28%). However, by 12 weeks, levels in both groups were similar, With a median follow-up of 61 months, 10 and 11 relapses, respectively, have been reported in the 30- and 20-Gy groups (hazard ratio, 1.11; 90% Cl, 0.54 to 2.28). The absolute difference in 2-year relapse rates is 0.7%; the lower 90% confidence limit is 2.9%. Only one patient has died from seminoma (allocated to the 20-Gy treatment group). Conclusion Treatment with 20 Gy in 10 fractions is unlikely to produce relapse rates more than 3% higher than for standard 30 Gy radiation therapy, and data on an additional 469 patients randomly assigned in a subsequent trial support and strengthen these results. Reductions in morbidity enable patients to return to work more rapidly. Prolonged follow-up is required before any inference can be made about any impact of allocated treatment on new primary cancer diagnoses.