Single-dose Carboplatin comparable to prophylactic radiotherapy for stage I seminoma

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Apr 17 2006

The risk of relapse for patients with stage I seminoma has traditionally ranged between 10 and 15%, depending on the local pathological characteristics of the tumor.

In the past, prophylactic retroperitoneal radiotherapy was recommended for the majority of these patients to decrease the risk of recurrence. However, as the potential risk of long-term gastrointestinal complications and secondary malignancies has been recognized, many patients with low-risk tumors are managed with watchful surveillance. Some have suggested single dose chemotherapy as an alternative to radiotherapy in select patients.

In the July 2005 issue of the Lancet, Oliver and colleagues report data from the EORTC evaluating the efficacy of radiotherapy versus single-dose carboplatin for patients with stage I seminoma.

Over a period of 5 years, 1477 patients were prospectively randomized to a single dose of carboplatin (adjusted for renal function) or retroperitoneal radiotherapy. Radiotherapy was administered as a para-aortic or dog-leg field. After a median follow-up of 4 years, there was no difference in recurrence-free survival between the radiotherapy (96.7%) and chemotherapy arms (97.7%, p = 0.32). These differences persisted with both intent-to-treat and per protocol analyses. There were minimal differences in toxicity, with patients in the carboplatin exhibiting less lethargy and a lower likelihood of missing work. Patients in the carboplatin arm also exhibited a lower risk for contralateral testicular tumors compared with the radiotherapy arm (Hazard ratio: 1.96, 95% confidence interval 1.0 to 3.8; p < 0.05).

This trial performed in a prospective randomized fashion but with limited follow-up showed that one prophylactic dose of carboplatin was as effective as retroperitoneal radiotherapy in preventing recurrence. The bar has been set very high for the treatment of stage I seminoma. Controlled trials of patients followed conservatively have shown that observation is a very reasonable strategy for small localized seminomas. While both carboplatin and radiotherapy seem to be equally effective in the short-term in preventing recurrence, the most important unanswered question is whether one treatment will outperform the other with regards to secondary malignancies and long-term complications.

By Ricardo F. Sánchez-Ortiz, MD

Lancet 2005 Jul 23-29; 366 (9482): 293-300.