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Extragonadal germ cell tumors: relation to testicular neoplasia and management options

An unselected population of 635 consecutive extragonadal GCT patients (EGCT) treated between 1975 through 1996 at 11 cancer centers was retrospectively evaluated for clinical prognosis and biological features of this disease. Five hundred twenty‐four patients (83%) had a nonseminomatous GCT, and 104 patients (16%) a seminomatous histology; 341 (54%) patients had a primary mediastinal EGCT, and 283 patients (45%) a retroperitoneal EGCT. Following platinum based induction chemotherapy±secondary surgery, 141 patients (49%) with mediastinal nonseminomas (median follow up period: 19 months) and 144 patients (63%) with retroperitoneal nonseminoma (median follow up period: 29 months) are alive [p=0.0006]. In contrast, the overall survival rate for patients with seminomatous EGCT is 88% with no difference between patients with mediastinal or retroperitoneal tumor location (median follow up period: 49 months). Multivariate analysis revealed nonseminomatous histology, the presence of non‐pulmonary visceral metastases, primary mediastinal GCT location, and elevated β‐HCG as independent prognostic factors for shorter survival. Sixteen patients (4.1%) developed a metachronous testicular cancer despite the use of platinum based chemotherapy. The cumulative risk of developing a MTC 10‐years after a diagnosis of EGCT was 10.3% (95% CI=4.9 to 15.6%), but higher among patients with nonseminomatous EGCT (14.3%; 95% CI=6.7 to 21.9%) or retroperitoneal EGCT location (14.2%; 95% CI=5.6 to 22.8%) than among patients with seminomatous EGCT (1.4%; 95% CI=0.0 to 4.2) or mediastinal EGCT location (6.2%; 95% CI=0.1 to 12.2). After a median follow‐up of 51 months (range=1 to 154 months), all 16 MTC patients were alive without disease. Patients with pure seminomatous EGCT histology have a long term chance of cure of almost 90% irrespective of the primary tumor site. Patients with mediastinal nonseminomas have a five‐years survival rate of 45%. This outcome is clearly inferior compared to patients with nonseminomatous retroperitoneal primaries who have a five‐year survival rate of 62%.