Recurrent seminomas: clinical features and biologic implications

Certain patients with seminoma and clinically atypical phenotypes--visceral metastases, elevated levels of β human chorionic gonadotropin (βHCG), and/or recurrent disease--have a poor prognosis. The primary goal of this pilot study was to characterize the clinical characteristics and treatment profile of these rare patients. We also wished to test whether these tumors expressed any specific biomarkers that might distinguish them as a unique subtype of seminoma.

We retrospectively identified 25 patients with a history of seminoma plus visceral metastases, βHCG levels >200 mU/ml, and/or recurrent disease. We reviewed these patients' histories for treatment efficacy and clinical outcome. Tissue samples were available from 6 of those patients, and we studied them for expression of the markers OCT 3/4, PLAP, CD30, TRA-1-60, c-kit, and gp200. We compared our results with the expression of those markers in tissue samples from mixed seminoma/embryonal carcinomas and classic seminomas.

Our analysis suggested that certain chemotherapeutic regimens (such as ifosfamide, paclitaxel, and cisplatin) are efficacious for the treatment of patients with these atypical seminomas. Further, specimens from the atypical seminomas generally had staining profiles that resembled those of classic seminomas and the seminoma components in mixed germ-cell tumors, but the profiles differed from those of the embryonal carcinoma components in the same mixed germ-cell tumors.

Although these atypical seminomas tend to be resistant to chemotherapy, they may still respond to certain chemotherapeutic regimens. Our pilot immunohistochemical study also suggested that the unique phenotypes associated with these atypical seminomas do not result from any relationship with embryonal carcinomas. More study is needed to confirm these initial findings.