FACTORS INFLUENCING THE PROGNOSIS OF POSTERIOR FOSSA TUMORS IN CHILDREN

Background: Although the prospect of survival of children with posterior fossa tumours has improved over the last two decades, major problems nevertheless remain. Objective: We have undertaken retrospective analysis of 100 children with posterior fossa tumor who were operated upon at our department from 1992 to 2004 to determine the factors which may influence the prognosis of these cases. Methods: Clinical data, radiological studies, operative notes and follow up sheets at both Neurosurgery and Radiotherapy Departments were reviewed. The different factors which may influence the outcome were evaluated. These factors included age, sex duration of symptoms, tumor type (medulloblastoma, astrocytoma, etc...), associated hydrocephalus, tumor location (midline versus lateral), brainstem involvement (either intrinsic or extrinsic), operative position (sitting versus prone), extent of tumor resection (total, subtotal, etc...), and type of adjuvant therapy (radiotherapy, chemotherapy or both). Results: Cerebellar astrocytoma was the most common tumor (36 cases) followed by medulloblastoma (32 cases), and brainstem glioma (16 cases). Ependymoma was present in only 10 cases and 6 cases had other tumors, CT scan and/or MRI showed associated obstructive hydrocephalus in 94 cases. V-P shunt was inserted preoperatively in 76 cases and postoperatively in 6 cases. Hydrocephalus was resolved spontaneously after tumor removal in 10 cases and after 3rd ventriculostomy in 2 cases. Sixty-four cases were operated upon in sitting position and thirty-six in prone position. Total tumor resection was achieved in 50% of medulloblastoma cases, 33% of astrocytoma cases and 20% of ependymoma cases. No total or even subtotal resection was achieved in patients with brainstem glioma. The surgical outcome for all tumors was excellent in 30% of cases, good in 32% of cases, fair in 18% and poor in 10%. Ten patients died intra- or post-operatively. Postoperative recurrence of the tumour was observed in 26% of cases. The overall survival rates were 76%, 58% and 37.5% at 1, 5 and 10 years respectively. The patients with cerebellar astrocytoma had the best prognosis, followed by medulloblastoma and ependymoma. No patient with brain stem glioma had survived more than 3 years after surgery. Conclusion: Two factors were found to have a significant association with prognosis i.e. extent of tumor removal and brain stem involvement. Survival rates were significantly higher for patients with complete tumor resection and patients with no brain stem involvement. Other factors with better survival rates but statistically insignificant include patient age above 10 years, long duration of symptoms, lateral tumor location, tumour type and postoperative adjuvant therapy.