Adjuvant treatment of clinical stage I seminoma: is a single course of carboplatin sufficient?

OBJECTIVES Adjuvant radiotherapy produces excellent disease-free rates in clinical Stage I seminoma. However, concern is growing about side effects and late hazards of this treatment. Carboplatin has been suggested to supplant radiotherapy. To date, there is little experience with this drug in the adjuvant treatment of seminoma. In particular, it is unclear whether one or two courses should be administered. METHODS In a nonrandomized study, 125 patients with pure clinical Stage I seminoma were given adjuvant carboplatin treatment (400 mg/m2). Ninety-three patients received one course and 32 two courses. The median follow-up time was 48 months. To assess gonadal toxicity, serial measurements of follicle-stimulating hormone (FSH) levels were done. To assess myelotoxicity, platelet counts at 3 and 4 weeks after treatment were monitored. RESULTS There were no relapses after two courses of carboplatin. After one course of carboplatin, eight relapses occurred (8.6%; 95% confidence interval [CI] 3.79% to 16.2%). All the relapses were located in the para-aortic region, and all the patients were rescued with cisplatin-based chemotherapy. The median time to recurrence was 16 months. The 5-year actuarial progression-free survival rate after one course was 91.1% (95% CI 85.25% to 97.01%). Younger patients (age groups: less than 30 years and 31 to 38 years) had relapses more frequently (P = 0.038) than those in the older age group (greater than 38 years). After 3 weeks, 32% of the patients had platelet counts below 150/nL. The median FSH level increased immediately after treatment, reaching a peak of 13.6 U/L. After 20 months, the median FSH level had returned to the normal range. CONCLUSIONS One adjuvant course of carboplatin was associated with low myelotoxicity and low gonadal toxicity; however, the recurrence rate was almost 9% and thus unsatisfactory. After two courses of carboplatin, no relapse was observed. Thus, the two-course regimen of carboplatin appears to be equivalent to radiotherapy, and because of its favorable toxicity profile, this regimen should be investigated in randomized trials.