Craniospinal irradiation of medulloblastoma in the supine position

Abstract

Background

Medulloblastoma, a primitive neuroectodermal tumour growing in the cerebellum, is one of the most sensitive childhood brain tumours to radiation therapy. The most common malignant CNS tumour of children is medulloblastoma with an overall incidence among children aged 0–19 years of 16–20% of all paediatric brain tumours. Radiotherapy is an essential method of treatment for these tumours, but surgery is the primary treatment of choice in medulloblastoma. Postoperative radiation therapy has a significant impact on local control and overall survival.

Aim

Medulloblastoma is the most common malignant brain tumour of children. The tumour is sensitive to chemotherapy and radiotherapy. Radiotherapy is an essential method of treatment for these tumours, but surgery is the primary treatment of choice in medulloblastoma.

Materials/Methods

Between January 1997 and March 2005 there were in this study post-operatively irradiated a total number of 33 paediatric patients aged under 15 years (median age 6.6 years) with medulloblastoma. All tumours were histologically proven and were located infratentorially in the posterior fossa. All of the patients were irradiated with a dose of 24–36 Gy to the whole craniospinal axis and boost with conformal therapy restricted to the tumour bed to the total dose of 50–54 Gy (30–36 Gy “high risk”, 24–30 Gy “standard risk” group). 26 patients (78%) received chemotherapy. Patients with craniospinal irradiation were placed in the supine position and fixed by a vacuum-form body immobilizer and head mask. Irradiation was performed using standard fractionation (5 fractions per week) with a single dose of 1.5–1.8 Gy for craniospinal axis by photon beam (6MV) of the linear accelerator.

Results

The median overall survival for the whole group was 55.3 months. The median disease-free survival was 20.6 months. The overall survival rate at 5 years was 41%; 8 patients (24%) died. No relationship was found between survival and age, sex or tumour size. Endocrine deficits occurred in 30% (8 patients of the group were hypothyroid, growth retardation occurred in 7 patients).

Conclusions

Results of overall and disease-free survival and side-effects of the technique of craniospinal axis irradiation in supine position are comparable with results of the technique in prone position.