Fractionated stereotactic radiotherapy of brain metastases: results of a retrospective study

Radiation Oncology

Table 2 Characteristics of brain metastases treated with 6 × 5 Gy fractionated stereotactic radiotherapy (n = 103)

Characteristics	Value
Location, n (%)
Supratentorial	81 (78.6%)
Infratentorial	22 (21.4%)
Gross tumor volume, GTV (cm³)
Mean (Standard deviation, SD)	2.6 (4.5)
Median (Interquartile range, IQR)	0.9 (0.4, 3.6)
Planning target volume, PTV (cm³)
Mean (SD)	7.5 (9.7)
Median (IQR)	3.4 (1.8, 9.3)
Response of the metastases on 1st follow-up MRI after a median time of 48 days (IQR 39.0, 61.0), n (%)
Responsive disease *^,†	55 (53.4%)
Stable disease ‡	38 (36.9%)
Progressive disease §	10 (9.7%)

SD: standard deviation; IQR: interquartile range; GTV: gross tumor volume, PTV: planning target volume, MRI: magnetic resonance imaging
* Complete response (disappearance of the brain metastasis on follow-up MRI) and partial response (at least a 30% decrease in the sum longest diameter of the brain metastasis) were summarized as responsive disease
† Including 5 brain metastases of 4 patients with brain radiation necrosis: Four brain metastases showed radiographically signs of brain radiation necrosis (patients had no neurological symptoms) and regression of enhancing areas on serial follow-up MRIs. There was 1 biopsy proven brain radiation necrosis of a brain metastasis of a patient with neurologic deficits. Histology showed no residual tumor cells. All 4 patients with brain radiation necrosis (4 x malignant melanoma, 1 x adrenal cancer) received immunotherapy at the time of diagnosis of brain radiation necrosis
‡ Stable disease was defined as neither fulfilling the criteria for partial response nor progressive disease
§ Progressive disease was defined as at least a 20% increase in the sum longest diameter of the brain metastasis and an increase by 5 mm or more

ISSN: 1748-717X