Randomized trials in 2466 patients with stage I seminoma: patterns of relapse and follow-up

Background From July 1, 1989, through March 31, 2001, 2466 patients with stage I seminoma were evaluated in three randomized noninferiority trials: the TE10, TE18, and TE19 trials. We analyzed mature results of these studies. Methods The TE10 trial randomly assigned 478 patients to para-aortic and ipsilateral iliac lymph node (dogleg field) or para-aortic only radiation therapy (total dose = 30 Gy). The TE18 trial randomly assigned 1094 patients to a total dose of 30 or 20 Gy of radiation therapy, predominantly to a para-aortic field. The TE19 trial randomly assigned 1477 patients to radiation therapy or a single injection of carboplatin at a dose of seven times the area under the curve. Time to relapse was determined from Kaplan-Meier curves, and such data were compared by use of Cox regression models. Noninferiority in TE18 and TE19 required the upper limit of the 90% confidence intervals (CIs) (reflecting the one-sided test for noninferiority at a 5% statistical significance level) to exclude a hazard ratio (HR) of greater than 2.0 and a doubling of the 5-year relapse rates observed in the control arm. The TE10 trial was not powered to exclude clinically relevant differences in overall relapse rates but was assessed against the same criteria. Results Median follow-up times were 6.4-12 years in the three trials. We identified the noninferiority of the following treatments: 20 Gy of radiation therapy in the TE18 trial (HR of relapse = 0.63, 90% CI = 0.38 to 1.04) and carboplatin in the TE19 trial (HR of relapse = 1.25, 90% CI = 0.83 to 1.89). Para-aortic radiation therapy in the TE10 trial was associated with a hazard ratio of relapse of 1.15 (90% CI = 0.54 to 2.44). Relapse occurred after 3 years in only four (0.2%) of all 2466 patients. Computed tomography scans had little impact on the detection of relapse after radiation therapy; seven of the 904 patients allocated radiation therapy in TE19 had a relapse detected by this method. Conclusion This large and mature dataset from three randomized trials has provided support for the use of either radiation therapy or carboplatin therapy as adjuvant treatment for stage I seminoma.