We reviewed the data of children with high-stage primitive neuroectodermal tumors (medulloblastomas) who were treated on Children's Cancer Group-921 protocol to evaluate the correlation between tumor resection and prognosis. Patients enrolled in the study had either tumors that were operatively categorized to be Chang tumor stage 3b or 4, postoperative residual tumors > 1.5 cm2, or evidence of tumor dissemination (Chang metastasis Stages [M Stages] 1-4) at diagnosis. Resections were analyzed in two ways, as follows: 1) by the extent of resection (percent of the tumor that was removed), as estimated by the treating neurosurgeon; and 2) by the extent of residual tumor (how much of the tumor was left), as estimated from postoperative scans. Two hundred and three children were enrolled in the study with institutional diagnoses of primitive neuroectodermal tumors-medulloblastomas; diagnoses were confirmed by central neuropathological review in 188 patients. Progression-free survival (PFS) at 5 years was 54% (standard error, 5%). As in previous Children's Cancer Group studies, age and M stage correlated with survival; PFS was significantly lower in children 1.5 to 3.0 years old at diagnosis and in those with any evidence of tumor dissemination (M Stage 1-4). On univariate analysis, neither extent of resection nor extent of residual tumor correlated with PFS. However, adjusting for other factors, extent of residual tumor was important; PFS was 20% (standard error, 14%) better at 5 years in children with no dissemination (M Stage 0) who had< 1.5 cm2 of residual tumor (P = 0.065) and was 24% (standard error, 14%) better at 5 years in children > 3 years old with no tumor dissemination (M Stage 0) and with < 1.5 cm2 residual tumor (P = 0.033). On the basis of our observations, we conclude that extent of tumor resection, as estimated by the neurosurgeon, does not correlate with outcome but that extent of residual tumor does correlate with prognosis in certain children (those who are > 3 years old, with no tumor dissemination). In contrast to age and M stage, the major factors associated with outcome, residual tumor is an important variable in outcome, one that neurosurgeons can control.

Pediatric neurosurgeons are more likely than general neurosurgeons to extensively remove malignant pediatric brain tumors. In these tumors, extent of removal has been demonstrated to influence survival.

To determine the current neurosurgical treatment of children with medulloblastomas, we reviewed the operative reports and neurosurgical report forms from 141 children with posterior fossa medulloblastomas treated on two current Children’s Cancer Study Group (CCSG) protocols, CCG-921 for high-stage and CCG-923 for low-stage medulloblastoma. Most medulloblastoma operations were performed in major medical centers: 61% of the operations were performed in CCSG member institutions, 23% in CCSG affiliates and 16% in other institutions. The tumor T stage distribution was as follows: T1 – 4%, T2 – 15%, T3A – 35%, T3B – 36%, and T4 – 10%. Tumors infiltrated the brainstem in 38% of cases and were associated with hydrocephalus in 91% of cases. Hydrocephalus was managed by external ventricular drains in 50% and by shunts in 60%. Adjunctive instruments (e.g., microscope, ultrasonic aspirator) were used in 93% of the operations. Tumor removals were as follows: biopsy only 3%, partial removals 13%, subtotal removals 13%, near total removals 41% and gross total removals in 40%; 90% or more of the tumor was removed in 81% of the operations. Forty-seven percent of the operations were performed by pediatric neurosurgeons. Near total and gross total removals were performed significantly more often (p < 0.05) by pediatric neurosurgeons than by general neurosurgeons. Postoperative morbidity was reported in 46% of cases, including neurologic morbidity in 26% of cases. There was no significant difference in patient morbidity between pediatric and general neurosurgeons.