Modified grading system for clinical outcome of intracranial non-germinomatous malignant germ cell tumors

Abstract

This study investigated the clinical outcome of intracranial non-germinomatous malignant germ cell tumors (NGMGCTs). All histologically proven cases of NGMGCTs treated in Shanghai Huashan Hospital, Fudan University were reviewed. A total of 39 cases were analyzed. There were 15 mixed germ cell tumors, 15 immature teratomas, 7 embryonal carcinomas and 2 yolk sac tumors. Patients were treated surgically first, followed by radiotherapy and/or chemotherapy. Some patients also received gamma knife surgery. The common 5-year survival rate was 36.8%. According to Matsutani's grading system, the 5-year actuarial survival rate for patients in the intermediate and poor prognosis groups were 45.8 and 14.3%, respectively. Individual analysis of each type of tumor showed that the median survival time of embryonal carcinoma was 27 months, which is very close to that of the intermediate group (28 months). We therefore classified embryonal carcinoma into the intermediate group where the 5-year actuarial survival rate for patients in the new intermediate prognosis group was 42.6%. Further analysis of immature teratoma cases found that the 5-year survival rate of patients with immature teratoma who received gamma knife surgery is 100%. This rate exhibited a significant difference (P=0.0049) compared to that of patients who did not undergo gamma knife surgery. In conclusion, we consider surgery as the first choice of treatment although for different histologis, the type of the tumor should be treated separately.

Figure 1

The survival curve of 39 patients with intracranial NGMGCTs by histology (n=39). Group 1, immature teratoma (n=15); group 2, embryonal carcinoma (n=7); group 3, yolk sac tumor (n=2); group 4, mixed tumors mainly composed of germinoma or teratoma (n=13); group 5, mixed tumors mainly composed of choriocarcinoma, yolk sac tumor (n=2).

Figure 2

The comparison of post-operation survival rates of the intermediate prognosis and the poor prognosis groups (P=0.0003, n=39). Group 1, intermediate prognosis group (immature teratoma, embryonal carcinoma, mixed tumors mainly composed of germinoma or teratoma) (n=35); group 2, poor prognosis group (yolk sac tumor, mixed tumors mainly composed of choriocarcinoma, yolk sac tumor) (n=4).