Extragonadal germ cell tumors of the mediastinum and retroperitoneum: results from an international analysis.

PURPOSE: To characterize the clinical and biologic features of extragonadal germ cell tumor (EGCT) and to determine the overall outcome with currently available treatment strategies.

PATIENTS AND

METHODS

Of an unselected population of 635 consecutive patients treated from 1975 through 1996 at 11 cancer centers, 341 patients (54%) had primary mediastinal EGCT, and 283 patients (45%) had retroperitoneal EGCT. Five hundred twenty-four patients (83%) had a nonseminomatous germ cell tumor (GCT), and 104 patients (16%) had a seminomatous histology.

RESULTS

After platinum-based induction chemotherapy with or without secondary surgery, 141 patients (49%) with mediastinal nonseminomas (median follow-up, 19 months; range, 1 to 178 months) and 144 patients (63%) with retroperitoneal nonseminoma (median follow-up, 29 months; range, 1 to 203 months) are alive (P =.0006). In contrast, the overall survival rate for patients with a seminomatous EGCT is 88%, with no difference between patients with mediastinal or retroperitoneal tumor location (median follow-up, 49 months; range, 4 to 193 months; respective 70 months; range, 1 to 211 months). A significantly lower progression-free survival rate was found in seminoma patients treated with initial radiotherapy alone compared with chemotherapy. Nonseminomatous histology, presence of nonpulmonary visceral metastases, primary mediastinal GCT location, and elevated beta-human chorionic gonadotropin were independent prognostic factors for shorter survival. Hematologic malignancies (n = 17) occurred without exception in patients with primary mediastinal nonseminoma. Sixteen patients developed a metachronous testicular cancer despite the use of platinum-based chemotherapy.

CONCLUSION

Whereas patients with pure seminomatous EGCT histology have a long-term chance of cure of almost 90% irrespective of the primary tumor site, 45% of patients with mediastinal nonseminomas are alive at 5 years. This outcome is clearly inferior compared with patients with nonseminomatous retroperitoneal primary tumors.