Incidence, treatment, and survival analysis in mediastinal malignant teratoma population.

Background: Mediastinal malignant teratoma, as a germ cell tumor, is rare and lacking of population-based study. This study aims to illustrate the incidence, treatment and prognosis of mediastinal malignant teratoma by using a population-based database.

Methods: We gathered clinicopathological data (1975-2016) of malignant teratoma from the Surveillance, Epidemiology and End Results (SEER) database. Then we conducted analysis on the incidence, treatment and prognosis of mediastinal malignant teratoma and other malignant teratomas.

Results: A total of 5,550 cases were in our study cohort, including mediastinal malignant teratoma (n=133) and other malignant teratomas (n=5,417). The incidence of mediastinal malignant teratoma in 2016 was 0.004 per 100,000 persons. Both overall survival (OS) and cancer-specific survival (CSS) of mediastinal malignant teratoma were significantly worse than those of other malignant teratomas (both P<0.001). Surgery significantly improved OS and CSS of either early-staged or all-staged patients with mediastinal malignant teratoma (all P<0.001). However, both chemotherapy and radiotherapy negatively influenced both OS and CSS of patients with mediastinal malignant teratomas (all P<0.001). Besides, compared with surgery alone, combinational therapies like surgery + chemotherapy or surgery + radiotherapy were more harmful to OS and CSS (all P<0.001) of patients with mediastinal malignant teratoma.

Conclusions: Our population-based evidence showed that mediastinal malignant teratoma, a rare cancer, had worse prognosis compared with other malignant teratomas. Compared with chemotherapy and radiotherapy, surgery could yield more survival benefits for either early-staged or all-staged patients with mediastinal malignant teratoma. Adjuvant use of chemotherapy/radiotherapy to surgery cannot improve but potentially harm patient prognosis.