Flow cytometric and quantitative histological parameters to predict occult disease in clinical stage I nonseminomatous testicular germ cell tumors.

The goal of this study was to determine if deoxyribonucleic acid (DNA) flow cytometric and quantitative histological parameters could predict occult metastases in clinical stage I nonseminomatous testicular cancer. Archival paraffin primary tumor tissue was available from 36 clinical stage I nonseminomatous germ cell testicular cancer patients who all had retroperitoneal lymphadenectomy and followup defining 2 groups: pathological stage I (23) and occult pathological stage II (13). Archival blocks were microdissected and individual histological components were subjected to flow cytometry. In addition, the primary histology was reevaluated for vascular invasion and per cent composition of histological components of embryonal carcinoma and other histologies. For flow cytometry parameters, no tumor was uniformly diploid, and the DNA index and per cent S phase cells were not useful in differentiating stages. Although mean per cent S phase for the aneuploid cell population and proliferative index were significantly greater for stage II cases by univariate logistic regression analysis, they are approximately 70% accurate in predicting occult disease as single tests and were not significant by multivariate analysis. The calculation of per cent embryonal carcinoma was also significantly greater in stage II cancer by univariate logistic regression testing and remained significant by multivariate analysis. Vascular invasion was marginally predictive of occult disease but was also not significant by multivariate analysis. Calculating the percentage of embryonal carcinoma of a primary testicular tumor may be a useful method to assess clinical stage I cancer patients for risk of occult disease. A larger study is needed to confirm the importance of per cent embryonal carcinoma and to clarify further if flow cytometry in combination is useful.