Primary Mediastinal Nonseminomas: A Population-Based Surveillance, Epidemiology, and End Results Analysis

This study aimed to determine the disease characteristics and prognosis of patients with primary mediastinal nonseminomas (PMNS) in a Surveillance, Epidemiology, and End Results (SEER) analysis.

Demographic, treatment, and survival outcome data of cases with PMNS from 1975 to 2016 were retrieved. Cases with unknown variables mentioned in the analysis were excluded. Relative statistical methods were applied to analyze clinical characteristics and prognosis.

A total of 587 PMNS patients met the selection criteria, 526 of whom were men. The mean age of patients was 28 (1-85) y. A total of 511 PMNS patients had validated subtypes, including 172 mixed germ cell tumors, 117 yolk sac tumors, 111 malignant teratomas, 70 choriocarcinomas, and 41 embryonal carcinomas. Patients with yolk sac tumors had the highest 3-y cancer-specific survival (CSS) rate (66.9%), while those with choriocarcinoma and embryonal carcinoma showed the worst prognosis. Surgery + chemotherapy (46.2%) was the most common and effective treatment for each subtype of PMNS. Multivariate Cox proportional hazards analysis identified embryonal carcinoma, malignant teratoma, choriocarcinoma, tumor size >15 cm, nodal metastasis, and distant stage as risk factors. In contrast, surgery-based care and younger age were protective factors. Propensity score matching analysis revealed significant improvement in the 5-y CSS rate from 35.8% to 60.3% with surgery (P < 0.001). However, radiotherapy (P = 0.436) and chemotherapy (P = 0.978) showed no survival benefits.

10 percent of the PMNS patients were female. Choriocarcinomas and embryonal carcinomas had the worst prognosis. Surgery was demonstrated to be the only way to prolong survival time. Chemotherapy and radiotherapy had minimal effects on prognosis.