Overall survival analysis of adjuvant radiation versus observation in stage I testicular seminoma: a surveillance, epidemiology, and end results (SEER) analysis.

Objective: The standard adjuvant treatment for men with stage I testicular seminoma remains controversial within the literature. We analyzed survival rates in men with stage I seminoma who underwent adjuvant radiation therapy (RT) or observation (OB) after orchiectomy.

Methods: Data were obtained from the Surveillance, Epidemiology, and End Results program of the National Cancer Institute from 1973 to 2003. The primary end points were overall survival (OS) and cause-specific survival (CSS). Multivariate Cox regression models were used to study the significance of clinical variables: age at diagnosis, laterality of primary disease, race, and radiation group.

Results: Of 6764 patients eligible for analysis, 5265 were treated with RT and 1499 with OB. After a median follow-up of 7.6 years, the 5-, 10-, and 20-year OS rates for the RT versus OB were 97.9 versus 95.0, 94.8 versus 92.2, and 83.5 versus 84.1 (P=0.0047), respectively. The CSS rates for the same time periods were 99.6 versus 98.7, 99.4 versus 98.7, and 99.2 versus 98.7 (P=0.0015), respectively. Adjuvant RT was associated with improved CSS on multivariate analysis with hazard ratio of 0.37 (confidence interval, 0.20-0.70; P=0.0023).

Conclusions: Within this large US population analysis, adjuvant RT was associated with improved OS and CSS compared with OB for men with stage I testicular seminoma. Further studies are needed to determine whether modern RT techniques and field-size reductions may lead to greater improvements in the therapeutic ratio, in light of the trend toward chemotherapy as primary treatment.