Outcome for Supratentorial Primitive Neuroectodermal Tumors in Children

Children with supratentorial PNETs are generally considered to have a poor prognosis. As with medulloblastomas, the aggressive biology of these tumors results in a high risk of local recurrence with the potential for leptomeningeal dissemination.

Outcome After Surgery

• Surgery alone not used: This tumor is treated with multimodal therapies. Rapid treatment failure is expected when surgery is used without adjuvant therapies.

Outcome After Multimodal Therapies

• 25–49% overall survival rate: Compared to medulloblastomas, supratentorial PNETs appear to be more aggressive and less chemosensitive. With aggressive surgical resection, radiotherapy, and chemotherapy, overall survival rates for children with supratentorial PNETs have been reported to be 45–49% (8, 10, 17). The prognosis for children with supratentorial PNETs is generally worse than that for children with medulloblastomas. Better overall survival for children with supratentorial PNETs is generally associated with either high-dose chemotherapy and stem cell rescue, or up-front radiation therapy.
• Metastasis predicts local treatment failure: Metastatic disease at presentation (CSF, intracranial, or spinal) was the most important determinant of local failure rates/recurrence in the Children’s Cancer Group study of supratentorial PNETs (19). Interestingly, the stage at presentation did not influence outcome in the Head Start study (17) or the Canadian study (1).
• Predictors of poor prognosis: In children with supratentorial PNETs, young age at diagnosis, tumor necrosis, and incomplete surgical resection may be predictors of a poor prognosis (15). In part, the poor prognosis in younger children may reflect the reluctance to subject younger children to radiotherapy due to the potentially devastating late side effects of radiotherapy in this age group.
• Adults may fare better: Although the clinical and radiologic features of supratentorial PNETs seem to be similar for children and adults, there is a suggestion that supratentorial PNETs in adults are associated with better outcomes (18).
• Sex and location not predictive: Patient sex and the particular location of the supratentorial PNET in a child do not seem to influence outcome (10, 15). No histological or molecular genetic features have been shown to be associated with the overall outcome in children with supratentorial PNETs (8, 15, 18).
• Factors risking quality of life not known: There are, to date, no long-term studies of quality of life metrics in patients with supratentorial PNET. With increasing use of high-dose therapy in younger patients and continued use of craniospinal radiation in older children, coupled with incremental survival benefits, quality of life analysis might be an informative area of future study.

Recurrence, progression or dissemination

The treatment of disease recurrence, progression, or dissemination has yet to be formally evaluated for supratentorial PNETs. The potential options for treatment include repeat surgery, local radiotherapy, and high-dose chemotherapy.

• Local recurrence treated aggressively, including surgically: A general consensus exists that local disease recurrence or progression should be treated aggressively. In these situations, it is reasonable to consider the option of repeat surgery for repeat resection of tumor.
• Disseminated recurrence – consider experimental chemotherapy: When a supratentorial PNET becomes disseminated after initial resection and adjuvant therapy, patients typically undergo progressive clinical decline. In the case of disease dissemination, current chemotherapeutic options are of limited beneficial effect, and patients are often considered for more experimental chemotherapy.