IMMUNOHISTOCHEMICAL EXPRESSION OF P53 TUMOR-SUPPRESSOR GENE PROTEIN IN ADULT GERM-CELL TESTIS TUMORS - CLINICAL CORRELATION IN STAGE-I DISEASE

P53 tumor suppressor gene protein immunostaining was evaluated in the primary tumor of adult testicular germ cell cancer to assess if P53 ex pression would serve as a clinically useful tumor marker. Representati ve archival tissues from 152 orchiectomy specimens were studied for P5 3 immunohistochemistry. Seminoma and nonseminomatous germ cell tumor c onstituents revealed P53 expression via immunohistochemistry in 90% an d 94% of the cases, respectively. For seminoma, there was a trend towa rd decreased P53 expression with advancing stage. For nonseminomatous germ cell tumor, although all cellular components showed variable P53 expression, P53 expression in embryonal carcinoma constituents increas ed among stages of disease. A third of pathological stage I cancer pat ients exhibited 2+ or greater P53-embryonal staining compared with 61% with stage II (p = 0.0670) and 67% with stage III (p = 0.0815) diseas e, respectively (Kruskal-Wallis, 2-sided test). As a secondary objecti ve, we wanted to determine if P53 immunohistochemistry would be useful to predict occult disease in clinical stage I nonseminomatous germ ce ll tumor. This group was studied for P53-embryonal immunohistochemistr y, the presence of vascular invasion and the quantitative determinatio n of percentage of embryonal carcinoma in the primary tumor in a multi variate fashion to assess if these tests could be clinically useful to predict occult disease. Degree of P53 immunostaining of the embryonal component in the primary tumor was statistically greater for stage II by univariate logistic regression analysis (p = 0.0362). Similarly, t he per cent embryonal cancer (p = 0.0002) and vascular invasion (p = 0 .0005) were highly significant as predictors of occult stage II diseas e via the univariate testing. By multivariate logistic regression anal ysis, the model consisting of per cent embryonal cancer and vascular i nvasion provided the best prediction of occult disease in the clinical stage I cohort. In addition, this model had the highest sensitivity a nd specificity of all multivariate models considered. The addition of P53-embryonal staining did not improve predictability nor sensitivity/ specificity. The P53 tumor suppressor gene protein is expressed to som e degree in most testicular germ cell tumors and degree of staining/ex pression varies according to stage of disease. From the standpoint of a clinically useful primary tumor risk factor for predicting occult di sease, vascular invasion by the tumor and percentage of embryonal carc inoma component in the tumor are more useful than P53 immunohistochemi stry.