Primary central nervous system germ cell tumors

Abstract

The prognosis of primary germ cell tumors (germinal neoplasms) of the central nervous system varies, depending on the histology and size of tumor and the extent of disease at diagnosis. Although some patients receive therapy without a tissue diagnosis, it is strongly recommended that tumor tissue samples be obtained for accurate histologic diagnosis. Modern neurosurgical navigation techniques have made tissue sampling by stereotactic biopsy a safe and rapid method of determining tumor histology. Depending on tumor location, open surgical biopsy may be required in some patients. Typically, germinomas are exquisitely radiosensitive, although preirradiation chemotherapy reduces the total radiation exposure and may increase the cure rate. Induction cisplatin-based chemotherapy, followed by low-dose involved field radiotherapy, has excellent overall and relapse-free survival rates and is the optimal treatment for patients with germinomas. This combined chemoradiotherapy approach is associated with minimal endocrinopathy and minimal neurocognitive dysfunction. Patients with relapses after low-dose radiation therapy can respond well to salvage therapy (chemotherapy or chemoradiotherapy) without significant sequelae. Patients with nongerminomas respond best to chemotherapy combined with radiation, although the response and cure rates are lower compared to germinomas. Patients with residual masses and normal tumor markers after primary therapy should have a second-look resection because most patients have residual teratoma or necrotic tissue and can be spared additional chemotherapy or radiation. Pure mature teratomas are cured only by surgical extirpation. Immature central nervous system teratomas appear to benefit from radical surgical resection, but higher doses of locally directed radiotherapy are required with no benefit from the usual chemotherapy.