Recurrent Childhood CNS Embryonal Tumors
Note: Some citations in the text of this section are followed by a level of evidence. The PDQ editorial boards use a formal ranking system to help the reader judge the strength of evidence linked to the reported results of a therapeutic strategy. (Refer to the PDQ summary on Levels of Evidence for more information.)
Recurrence of all forms of central nervous system embryonal tumors is not uncommon, usually occurring within 18 months of treatment; however, recurrent tumors may develop many years after initial treatment.[1,2] Disease may recur at the primary site or may be disseminated at the time of relapse. Sites of noncontiguous relapse may include the spinal leptomeninges, intracranial sites, and cerebrospinal fluid, in isolation or in any combination, and is variably associated with primary tumor relapse.[1,2,3] One series has found that, independent of the dose of radiation therapy employed or the type of chemotherapy utilized, approximately one-third of patients will relapse at the primary tumor site alone, one-third will relapse at the primary tumor site plus distant sites, and one-third will relapse at distant sites without relapse at the primary site.[1,2,3] At the time of relapse, a complete evaluation for extent of recurrence is indicated for all embryonal tumors. Biopsy or surgical resection may be necessary for confirmation of relapse because other entities such as secondary tumors and treatment-related brain necrosis may be clinically indistinguishable from tumor recurrence. The need for surgical intervention must be individualized on the basis of the initial tumor type, the length of time between initial treatment and the reappearance of the lesion, and clinical symptomatology. Extraneural disease relapse may occur but is rare and is seen primarily in patients treated with radiation therapy alone.
Patients with recurrent embryonal tumors who have already received radiation therapy and chemotherapy may be candidates for salvage chemotherapy and/or stereotactic irradiation.[4] These tumors can be responsive to chemotherapeutic agents used singularly or in combination, including cyclophosphamide, cisplatin, carboplatin, lomustine, and etoposide.[5,6,7,8,9,10,11,12,13] Approximately 30% to 50% of these patients will have objective responses to conventional chemotherapy, but long-term disease control is rare. For select patients with recurrent medulloblastoma, primarily infants and young children who were treated at the time of diagnosis with chemotherapy alone and developed local recurrence, long-term disease control may be obtained after further treatment with chemotherapy plus local radiation therapy.[14][Level of evidence: 2A] For patients who have previously received radiation therapy, higher-dose chemotherapeutic regimens, supported with autologous bone marrow rescue or peripheral stem cell support, have been used with variable results.[15,16,17][Level of evidence: 2A]; [18][Level of evidence: 3iiB]; [19,20][Level of evidence: 3iiiA] With such regimens, objective response is frequent, occurring in 50% to 75% of patients; however, long-term disease control is obtained in fewer than 30% of patients and is primarily seen in patients in first relapse and in those with only localized disease at the time of relapse.[17]; [18][Level of evidence: 3iiB] Long-term disease control for patients with disseminated disease is infrequent.[21][Level of evidence: 3iA]
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