Impact of adjuvant fractionated stereotactic radiotherapy dose on local control of brain metastases
The aim of this study was to determine whether a higher biological effective dose (BED) would result in improved local control in patients treated with fractionated stereotactic radiotherapy (FSRT) for their resected brain metastases.
Patients with newly diagnosed brain metastases without previous brain radiotherapy were retrospectively reviewed. Patients underwent surgical resection of at least one brain metastasis and were treated with adjuvant FSRT, delivering 25–36 Gy in 5–6 fractions. Outcomes were computed using Kaplan–Meier survival analysis and univariate analysis.
Fifty-four patients with 63 post-operative cavities were included. Median follow-up was 16 months (3–60). Median metastasis size at diagnosis was 2.9 cm (0.6–8.1) and median planning target volume was 19.7 cm3 (6.3–68.1). Two-year local control (LC) was 83%. When stratified by dose, 2 years LC rate was 95.1% in those treated with 30–36 Gy in 5–6 fractions (BED10 of 48–57.6 Gy10) versus 59.1% lesions treated with 25 Gy in 5 fractions (BED10 of 37.5 Gy10) (p < 0.001). LC was not associated with resection cavity size. One year overall survival was 68.7%, and was independent of BED10. Symptomatic radiation necrosis occurred in 7.9% of patients and was not associated with dose.
In the post-operative setting, high-dose FSRT (BED10 > 37.5 Gy10) were associated with a significantly higher rate of LC compared to lower BED regimens. Overall, 25 Gy in 5 fractions is not an adequate dose to control microscopic disease. If selecting a 5-fraction regimen, 30 Gy in five fractions appears to provide excellent tumor bed control.
KeywordsFractionated stereotactic radiotherapy Brain metastases Radiation
Compliance with ethical standards
Conflict of interest
The authors declare they have no conflict of interest.
- 1.Andrews DW, Scott CB, Sperduto PW et al (2004) Whole brain radiation therapy with or without stereotactic radiosurgery boost for patients with one to three brain metastases: phase III results of the RTOG 9508 randomised trial. Lancet. https://doi.org/10.1016/S0140-6736(04)16250-8 CrossRefPubMedGoogle Scholar
- 3.Mahajan A, Ahmed S, McAleer MF et al (2017) Post-operative stereotactic radiosurgery versus observation for completely resected brain metastases: a single-centre, randomised, controlled, phase 3 trial. Lancet Oncol 18:1040–1048. https://doi.org/10.1016/S1470-2045(17)30414-X CrossRefPubMedPubMedCentralGoogle Scholar
- 6.Brown PD, Jaeckle K, Ballman KV et al (2016) Effect of radiosurgery alone vs radiosurgery with whole brain radiation therapy on cognitive function in patients with 1 to 3 brain metastases: a randomized clinical trial. JAMA 316:401–409. https://doi.org/10.1001/jama.2016.9839 CrossRefPubMedPubMedCentralGoogle Scholar
- 7.Brown PD, Ballman KV, Cerhan JH et al (2017) Postoperative stereotactic radiosurgery compared with whole brain radiotherapy for resected metastatic brain disease (NCCTG N107C/CEC.3): a multicentre, randomised, controlled, phase 3 trial. Lancet Oncol 18:1049–1060. https://doi.org/10.1016/S1470-2045(17)30441-2 CrossRefPubMedPubMedCentralGoogle Scholar
- 10.Minniti G, Scaringi C, Paolini S et al (2016) Single-fraction versus multifraction (3 × 9 Gy) stereotactic radiosurgery for large (> 2 cm) brain metastases: a comparative analysis of local control and risk of radiation-induced brain necrosis. Int J Radiat Oncol Biol Phys 95:1142–1148. https://doi.org/10.1016/j.ijrobp.2016.03.013 CrossRefPubMedGoogle Scholar