Observation versus adjuvant radiation or chemotherapy in the management of stage I seminoma: clinical outcomes and prognostic factors for relapse in a large US cohort.

Purpose: The management of stage I seminoma has evolved over the past 20 years. Contemporary management options after orchiectomy include adjuvant radiation, adjuvant chemotherapy, and observation. This analysis defines the experience at Kaiser Permanente Southern California from 1990 to 2010.