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

Source: https://onco.cc/key-papers/paper-kirkpatrick-srs-margin-trial-ijrobp-2015/  
OnCo record `paper-kirkpatrick-srs-margin-trial-ijrobp-2015` (Key paper). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Brain metastases treated with radiosurgery were randomly given a 1 millimetre or a 3 millimetre margin. Control of the treated tumours was similar, the larger margin irradiated more healthy brain, and five of the six biopsy-proven cases of radiation damage were in the 3 millimetre group.

## Summary

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.

## Fields

- Kind: Key paper
- Last checked: 2026-10-20
- Tags: precision; radiation
- Journal: International Journal of Radiation Oncology, Biology, Physics
- Year: 2015
- DOI: 10.1016/j.ijrobp.2014.09.004
- Authors: Kirkpatrick JP, Wang Z, Sampson JH, et al.
- Findings: 49 patients with 80 brain metastases were randomised lesion by lesion to a 1 mm or 3 mm margin.; Local recurrence was seen in 3 lesions (2 in the 1 mm group, P = .51); 6.7 per cent at 12 months.; Biopsy-proven radionecrosis occurred in 6 lesions, 5 in the 3 mm group (P = .10).; The volume receiving 12 Gy or more was significantly higher with the 3 mm margin.
- What it means: With image guidance, a larger safety margin around a brain metastasis did not buy better tumour control and added healthy brain to the high-dose region. It is one of the few randomised tests of a margin itself.
- Caveats: Small, single centre, and randomised by lesion rather than by patient.; The radionecrosis difference was not statistically significant (P = .10).; Median overall survival was 10.6 months, which limits how long late effects could be observed.

## Sources

- IJROBP 2015: https://doi.org/10.1016/j.ijrobp.2014.09.004
- PubMed 25442342: https://pubmed.ncbi.nlm.nih.gov/25442342/

## Connected records

- cancers: [Brain metastases (secondary brain tumours)](https://onco.cc/cancers/secondary-brain-tumours/), [Metastatic cancer (cancer that has spread)](https://onco.cc/cancers/metastatic-cancer/)
- fronts: [Radiation Therapy](https://onco.cc/fronts/radiation/)
- technologies: [IMRT / IGRT (modern external beam)](https://onco.cc/technologies/imrt-igrt/), [Stereotactic radiosurgery (Gamma Knife, CyberKnife, linac SRS)](https://onco.cc/technologies/radiosurgery-srs/)
- terms: [GTV, CTV and PTV (target volumes)](https://onco.cc/terms/planning-target-volume/), [Radiation necrosis (brain)](https://onco.cc/terms/radiation-necrosis/), [Stereotactic radiosurgery (SRS)](https://onco.cc/terms/stereotactic-radiosurgery/)
- journals: [International Journal of Radiation Oncology, Biology, Physics](https://onco.cc/journals/ijrobp/)

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