Defining the optimal planning target volume in image-guided stereotactic radiosurgery of brain metastases: results of a randomized trial

Kirkpatrick and colleagues randomised individual brain metastases in adults with one to three lesions under 4 cm to a 1 mm or a 3 mm uniform expansion of the gross tumour volume drawn on contrast MRI, treated on a linear accelerator with image guidance. Between 2010 and 2012, 49 patients with 80 metastases were treated. The 3 mm group had a significantly higher ratio of treated to visible volume and a larger volume receiving 12 Gy or more. Local recurrence occurred in only 3 lesions (2 in the 1 mm group, P = .51), 6.7 per cent at 12 months. Biopsy-proven radionecrosis alone occurred in 6 lesions, 5 of them in the 3 mm group (P = .10). No significant change in neurocognition or quality of life was seen at three months. The authors concluded that a 1 mm expansion is more appropriate.