Pilocytic Astrocytomas In Children Research Articles

Study of the MIB-1 labeling index as a predictor of tumor progression in pilocytic astrocytomas in children and adolescents.

The pilocytic astrocytoma (PA) is the most common childhood brain tumor. This report examines the MIB-1 labeling index (LI) as a predictor of progression-free survival (PFS) among childhood PAs. Consecutive PAs were examined to determine whether the MIB-1 LI was associated with tumor progression. Other variables evaluated included tumor location, use of adjuvant therapy, extent of resection, and age at diagnosis. One hundred forty-one children were identified (mean +/- SD age, 7.6 +/- 4.7 years; range, 0.43 to 18.56 years); 118 children had adequate tissue for MIB-1 immunohistochemistry. The 5-year PFS was 61.25%. By log-rank analysis, an MIB-1 LI of more than 2.0 was associated with shortened PFS (P =.035). Patients with PAs who underwent complete surgical resection, had tumors located in the cerebellum, and were treated with surgery only also had more prolonged PFS (P =.001 for all). Tumors in the optic pathways were associated with a shorter PFS (P =.001). Restricting the evaluation of MIB-1 LI to only incompletely resected tumors revealed an insignificant trend of MIB-1 LI of more than 2.0 having a shortened PFS. Multivariate analysis demonstrated completely resected tumors and tumors located in the cerebellum as less likely to progress (P =.001 and.019, respectively). Children with PAs with an MIB-1 LI of more than 2.0 have a shortened PFS. PAs that are completely resected and are located in the cerebellum have a prolonged PFS. This initial study suggests that the MIB-1 LI identifies a more aggressive subset of PAs. Further work should focus on elucidating features of pilocytic astocytomas that will identify prospectively children at risk for progression.

Second Surgery for Recurrent Pilocytic Astrocytoma in Children

Pilocytic astrocytoma (PA) is the most common childhood brain tumor. In cases where the tumor progresses or recurs following primary surgical resection, the appropriate treatment is unclear. Options include chemotherapy, radiation therapy, surgical resection or a combination thereof. To analyze the utility of further surgery, we performed a retrospective, single-institution review of pediatric patients with recurrent PAs from 1990 to 1999 who were treated with a second surgical resection. Patients were excluded if they received adjuvant chemotherapy or radiation therapy. Twenty cases were identified. Tumor locations included: cerebral hemisphere (3), cerebellum (7), optic pathway/hypothalamus (5), thalamus (1) and brainstem (4). The indication for 4 surgeries included an enlarging tumor-associated cyst. At second surgery, 10 of 20 patients had a gross total resection (GTR), 2 a near total resection (NTR), and the remaining 8 patients had a subtotal resection (STR). No patients have died. Two of 10 tumors after GTR, 0 of 2 tumors after NTR, and 7 of 8 tumors after STR had second recurrence/progression at a mean of 15 months (range 4–33 months) following second surgery. The remaining 11 patients are recurrence/progression-free at a mean of 40.7 months (range 19–119 months). Surgery for tumors or midline structures rarely resulted in a GTR (1 of 10 cases). Surgery for tumors located in the cerebral hemispheres or cerebellum resulted in GTR or NTR in all cases and can result in long periods of progression-free survival without further adjuvant treatment.

Early outcomes after stereotactic radiosurgery for growing pilocytic astrocytomas in children.

To examine the role of stereotactic radiosurgery in the adjuvant management of children with growing and unresectable deep-seated pilocytic astrocytomas, we reviewed our experience in 9 patients. The tumors were located in the dorsolateral pons (n = 2), midbrain (n = 1, cerebellar peduncle (n = 2), thalamus (n = 1), temporal lobe (n = 1), hypothalamus (n = 1), and caudate nucleus (n = 1). The mean tumor diameter was 16 mm (range, 11-25 mm). Seven patients had prior partial tumor resection, and 2 had a stereotactic biopsy. Two patients had failed fractionated radiotherapy and 7 were considered at risk for adverse radiation effects because of their age. The mean dose to the tumor margin at radiosurgery was 15 Gy (range, 12-18). During mean follow-up of 19 months (range 13-41 months), there was a marked decrease in tumor size in 5 patients; 4 patients had no further growth. No early or delayed morbidity was associated with radiosurgery. Gamma knife radiosurgery proved a safe and effective therapeutic tool in the management of children with deep, small volume pilocytic astrocytomas. Because this tumor often appears well-delineated on contrast-enhanced neuroimaging, we believe that conformal radiosurgical targeting accurately irradiates tumor cells. For small tumor volumes it can be used in place of fractionated larger-field radiotherapy. The ability to treat the tumor yet spare surrounding brain may reduce the surgical morbidity associated with attempted radical resection and the potential cognitive and endocrine disabilities associated with fractionated radiation therapy.