Primitive Neuroectodermal Tumors of the Central Nervous System Treatment & Management

Updated: May 31, 2018
  • Author: Subrata Ghosh, MD, MBBS, MS; Chief Editor: Tarakad S Ramachandran, MBBS, MBA, MPH, FAAN, FACP, FAHA, FRCP, FRCPC, FRS, LRCP, MRCP, MRCS  more...
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Treatment

Medical Care

Preoperative administration of steroids can help to alleviate some of the signs and symptoms of primitive neuroectodermal tumors (PNET) by reducing peritumoral edema. [2]

Radiation therapy

Radiation therapy, usually given adjuvantly, should be performed under the direction of a radiation oncologist.

Many series report a clear, dose-dependent relationship between postoperative radiation and local tumor control.

Adjuvant radiotherapy alone, with posterior fossa doses of 5000 cGy and neuraxis doses of 3000 cGy, results in a 5-year event-free survival rate of 50-70%. Lower than standard doses of radiation therapy, at least without chemotherapy, are less effective.

Craniospinal axis radiation is used for patients with spinal dissemination.

Newer methods, including stereotactic radiosurgery and high fractionation radiotherapy, are being evaluated. [12] These methods limit the dose of radiation to the local sites and avoid potential adverse effects in children, including cognitive dysfunction or delay in growth, that are seen frequently with conventional radiotherapy.

Chemotherapy

Chemotherapy should be administered under the direction of a medical oncologist.

Varying combinations of drugs used in these tumors include, but are not limited to, lomustine (CCNU), vincristine, cisplatin, etoposide (VP-16), and cyclophosphamide. Several trials, including those from the Pediatric Oncology Group (POG) and Children's Cancer Group (CCG), are underway, evaluating varying combinations of chemotherapy with and without radiotherapy. The best results, so far, have come from the Children's Hospital of Pennsylvania study, reporting a 5-year event-free survival rate of 80% among 51 patients.

CCNU has been shown to be of limited benefit, particularly in high-risk cases.

High-dose chemotherapy with stem cell rescue is being tried to improve survival and outcome.

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Surgical Care

The goals of surgery are to achieve radical tumor resection, when possible, and to restore normal CSF outflow.

For persistent lesions, second-look surgery is recommended to remove residual tumor.

Available studies have failed to show a significant advantage, in terms of event-free survival, of total resection as compared to near-total and less-aggressive resections.

Permanent CSF diversion in the form of ventriculoperitoneal shunt is required in as many as 30% of these cases.

Current treatment modalities include a combination of surgery, chemotherapy, and/or radiation. Ongoing worldwide research has explored nonconventional therapeutic strategies such as immunotherapy and gene therapy to improve outcome and survival, although their clinical efficacy is yet to be established. [13] Moreover, there is growing interest in proton therapy as a potential replacement for photon therapy, while high-dose chemotherapy and autologous stem cell rescue may improve therapeutic efficacies.

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Consultations

Consultation with the following may prove helpful:

  • Neurosurgeon

  • Neurologist/pediatric neurologist

  • Radiation oncologist

  • Medical oncologist

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