Radiothérapie en conditions stéréotaxiques des métastases cérébrales

Stereotactic radiotherapy of brain metastases is increasingly proposed after polydisciplinary debates among experts. Its definition and modalities of prescription, indications and clinical interest regarding the balance between efficacy versus toxicity need to be discussed. Stereotactic radiotherapy is a 'high precision' irradiation technique (within 1. mm), using different machines (with invasive contention or frameless, photons X or gamma) delivering high doses (4to 25. Gy) in a limited number of fractions (usually 1to 5, ten maximum) with a high dose gradient. Dose prescription will depend on materials, dose constraints to organs at risk varying with fractionation. Stereotactic radiotherapy may be proposed: (1) in combination with whole brain radiotherapy with the goal of increasing (modestly) overall survival of patients with a good performance status, 1to 3brain metastases and a controlled extracranial disease; (2) for recurrence of 1-3brain metastases after whole brain radiotherapy; (3) after complete resection of a large and/or symptomatic brain metastases; (4) after diagnosis of 3-5asymptomatic new or progressing brain metastases during systemic therapy, with the aim of delaying whole brain radiotherapy (avoiding its potential neurotoxicity) and maintaining a high focal control rate. Only a strict follow-up with clinical and MRI every 3months will permit to deliver iterative stereotactic radiotherapies without jeopardizing survival. Simultaneous delivering of stereotactic radiotherapy with targeted medicines should be carefully discussed.