PREVALENCE OF CONTRALATERAL TESTICULAR INTRAEPITHELIAL NEOPLASIA IN PATIENTS WITH TESTICULAR GERM-CELL NEOPLASMS

Purpose: Testicular intraepithelial neoplasia ([TIN], so-called carcin oma in situ of the testis) is hypothesized to be the precursor of test icular germ cell neoplasms. According to previous studies, it can be d etected by testicular biopsy. Since patients with a unilateral testicu lar tumor are at high risk of a second testicular tumor, it seemed fea sible to examine the prevalence of contralateral TIN in patients with testicular germ cell cancer and correlate it with the known prevalence of bilateral testicular tumors, The aim was to provide more evidence for the role of TIN as the preinvasive stage of testicular cancer. Pat ients and Methods: Nineteen hundred fifty-four consecutive patients wi th a unilateral testicular germ cell tumor underwent contralateral bio psy. All specimens were examined immunohistologically. Results: TIN wa s observed in 4.9% (95% confidence interval [CI], 3.95% to 5.91%). Tes ticular atrophy and a history of undescended testis were more frequent ly observed in patients with contralateral TIN, but only atrophy was s hown to be independently associated by multivariate analysis. Patients with testicular atrophy have a 4.3-fold increased risk of having cont ralateral TIN. Sixty-four percent of TIN cases were found in normal te stes. Patients with TIN were significantly younger than those without (P < .0017). Three patients developed a second testicular tumor despit e a negative biopsy for TIN. Conclusion: The prevalence of contralater al TIN corresponds well to the known prevalence of bilateral testicula r tumors. Testicular atrophy is a strong indicator for the presence of TIN, but approximately 60% of TIN cases occur without atrophy. The pr esent data are in accordance with the theory that TIN is an early step in the histogenesis of testicular germ cell neoplasms. (C) 1996 by Am erican Society of Clinical Oncology.