Incidence of metachronous testicular cancer in patients with extragonadal germ cell tumors

Background: The frequency of subsequent testicular cancer (referred to as m etachronous testicular cancer) in men who have had previous testicular canc er is relatively high. The rate of metachronous testicular cancer in men wi th extragonadal germ cell tumors (EGCTs), however, is largely unknown. We c onducted a retrospective study of EGCT patients to determine the incidence, cumulative risk, and specific risk factors for metachronous testicular can cers. Methods: A standardized questionnaire about patient characteristics, the extent of EGCT disease, any second malignancies, and treatments receive d was completed for 635 patients with EGCTs identified from the medical rec ords of 11 cancer centers in Europe and the United States from 1975 through 1996. Comparisons with age group-specific data from the Saarland, Germany, population-based cancer registry were used to calculate the standardized i ncidence ratio (SIR). The Kaplan-Meier method was used to analyze survival data and cumulative risk. All statistical tests were two-sided. Results: Si xteen EGCT patients (4.1%) developed metachronous testicular cancers, with a median time between diagnoses of 60 months (range, 14-102 months). The ri sk of developing metachronous testicular cancers was statistically signific antly increased in patients with EGCTs (observed = 16; expected = 0.26; SIR = 62; 95% confidence interval [CI] = 36 to 99) and in subsets of EGCT pati ents with mediastinal location (SIR = 31; 95% CI = 8 to 59), retroperitonea l location (SIR = 100; 95% CI = 54 to 172), and nonseminomatous histology ( SIR = 75; 95% CI = 43 to 123). The cumulative risk of developing a metachro nous testicular cancer 10 years after a diagnosis of EGCT was 10.3% (95% CI = 4.9% to 15.6%) and was higher among patients with nonseminomatous EGCTs (14.3%; 95% CI = 6.7% to 21.9%) and retroperitoneal EGCTs (14.2%; 95% CI = 5.6% to 22.8%) than among patients with seminomatous EGCTs (1.4%; 95% CI = 0.0% to 4.2%) and mediastinal EGCTs (6.2%; 95% CI = 0.1% to 12.2%). Conclus ions: Patients with EGCTs, particularly those with retroperitoneal or nonse minomatous tumors, but also those with primary mediastinal EGCTs, are at an increased risk of metachronous testicular cancer.