Risk of Contralateral Testicular Cancer: A Population-Based Study of 29515 U.S. Men

Background: Although risk estimates for synchronous and metachronous contralateral testicular cancers vary widely, many clinicians recommend routine biopsy of the contralateral testis for patients diagnosed with unilateral testicular cancer. We evaluated the risk of contralateral testicular cancer and survival in a large population-based cohort of men diagnosed with testicular cancer before age 55 years. Methods: For 29 515 testicular cancer cases reported to the National Cancer Institute’s Surveillance, Epidemiology and End Results Program from 1973 through 2001, we estimated the prevalence of synchronous contralateral testicular cancer, the observed-to-expected ratio (O/E) and 15-year cumulative risk of metachronous contralateral testicular cancer, and the 10-year overall survival rate of both synchronous and metachronous con tralateral testicular cancer, using the Kaplan – Meier method for the two latter assessments. Age-adjusted multivariable analyses were used to examine risk according to histologic type of the original cancer. Results: A total of 175 men presented with synchronous contralateral testicular cancer; 287 men developed metachronous contralateral testicular cancer (O/E = 12.4 [95% confi dence interval {CI} = 11.0 to 13.9]; 15-year cumulative risk = 1.9% [95% CI = 1.7% to 2.1%]). In the multivariable analysis, only nonseminomatous histology of the fi rst testicular cancer was associated with a statistically signifi cantly decreased risk of metachronous contralateral testicular cancer (hazard ratio [HR] = 0.60, 95% confi dence interval [CI] = 0.46 to 0.79; P<.001). Increasing age at fi rst testicular cancer diagnosis was associated with decreasing risk of nonseminomatous metachronous con tra lateral testicular cancer (odds ratio = 0.90, 95% CI = 0.86 to 0.94). The 10-year overall survival rate after metachronous contralateral testicular cancer diagnosis was 93% (95% CI = 88% to 96%), and that after synchronous contralateral testicular cancer was 85% (95% CI = 78% to 90%). Conclusions: The