Tumour recurrence vs radionecrosis: an indication for multitrajectory serial stereotactic biopsies

External RT has been proved to be an important adjuvant to surgery in the treatment of malignant glioma. It has also been demonstrated, that its effect on survival is dose-dependent, although accompanied by a higher morbidity. Intents to localize the field of high dose RT to the tumour area have been performed with the aim to spare damage of the normal brain tissue. Between August 1983 to December 1987, 40 patients with malignant astrocytoma (16 GM, 24 AA) underwent high dose localized hyperfractionated external RT after surgical resection. Patients received 57.6 Gy to the tumour and oedema area associated with a boost localized to the tumour of 7.4, 14.4 or 24 Gy. In the follow-up, 16 patients died with evidence of increase in size of lesion diagnosed by CT/MRI. Since July 1987, 12 patients with recurrence or increase on size of CT/MRI lesion have undergone multitrajectory serial stereotactic biopsies. From the biopsies 8 patients were histologically diagnosed was compatible with radionecrosis. From the 4 recurrences, 2 patients were treated with 125I implants and 1 with new resection. Patients with radionecrosis were treated with corticoides and diuretics, obtaining partial or complete remission of symptoms and decrease in size of CT lesion. Undoubtly, Multiplanar/3D multitrajectory serial stereotactic biopsies play a major role in the follow-up of these patients, and accurate diagnosis need to be established for further treatment therapy. The question remains if these localized boost should be replaced by 3D Multiplanar stereotactic interstitial radiotherapy boost after surgery and conventional radiotherapy.