Optimal Planning Target Volume for Stage I Testicular Seminoma: A Medical Research Council Randomized Trial

Abstract

PURPOSE: To compare relapse rates and toxicity associated with para-aortic (PA) strip or PA and ipsilateral iliac lymph node irradiation (dogleg [DL] field) (30 Gy/15 fractions/3 weeks) for stage I testicular seminoma. PATIENTS AND METHODS: Between July 1989 and May 1993, 478 men with testicular seminoma stage I (T1 to T3; no ipsilateral inguinoscrotal operation before orchiectomy) were randomized (PA, 236 patients; DL, 242 patients). RESULTS: Median follow-up time is 4.5 years. Eighteen relapses, nine in each treatment group, have occurred 4 to 35 months after radiotherapy; among these, four were pelvic relapses, all occurring after PA radiotherapy. However, the 95% confidence interval (CI) for the difference in pelvic relapse rates excludes differences of more than 4%. The 3-year relapse-free survival was 96% (95% CI, 94% to 99%) after PA radiotherapy and 96.6% (95% CI, 94% to 99%) after DL (difference, 0.6%; 95% confidence limits, −3.4%, +4.6%). One patient (PA field) has died from seminoma. Survival at 3 years was 99.3% for PA and 100% for DL radiotherapy. Acute toxicity (nausea, vomiting, leukopenia) was less frequent and less pronounced in patients in the PA arm. Within the first 18 months of follow-up, the sperm counts were significantly higher after PA than after DL irradiation. CONCLUSION: In patients with testicular seminoma stage I (T1 to T3) and with undisturbed lymphatic drainage, adjuvant radiotherapy confined to the PA lymph nodes is associated with reduced hematologic, gastrointestinal, and gonadal toxicity, but with a higher risk of pelvic recurrence, compared with DL radiotherapy. The recurrence rate is low with either treatment. PA radiotherapy is recommended as standard treatment in these patients.