ESTRO 38 Abstract book

S691 ESTRO 38

Low- grade (n=282)

High- grade (n=71)

Gender

73 (25.9%) 209 (74.1%)

41 (57.7%) 30 (42.3%)

M

W

Age

(median,

60 (11- 86)

62 (24- 84)

range) [years]

Resection

179 (63.5%)

70 (98.6%)

Conclusion PET-imaging improves the detection of tumor cells, especially during treatment planning. It showed a significant influence on OS and PFS. Further sub-analyses will investigate the influence of PET for resected patients, and large tumor volumes and establish cut-off values for which tumor sizes additional PET imaging might be beneficial. For low-grade meningiomas the time between resection and RT was borderline significant. With the factors age, PTV and gender a weighted scoring system will be developed for prognostic assessment. EP-1257 Post-operative hypo-fractionated SBRT in a large series of patients with brain metastases G. Martinage 1 , J. Geffrelot 2 , D. Stefan 2 , E. Bogart 3 , E. Rault 4 , N. Reyns 5 , E. Emery 6 , S. Martinage Makhloufi 7 , R. Mouttet Audouard 1 , L. Basson 1 , X. Mirabel 1 , E. Lartigau 1,8 , D. Pasquier 1,8 1 Centre Oscar Lambret, Academic Department of Radiation Oncology, Lille, France ; 2 Centre François Baclesse, Department of Radiation Oncology, Caen, France ; 3 Centre Oscar Lambret, Department of Biostatistics, Lille, France ; 4 Centre Oscar Lambret, Department of Medical Physics, Lille, France ; 5 CHRU Lille, Department of Neurosurgery, Lille, France ; 6 CHU Côte de Nacre, Neurosurgery department, Caen, France ; 7 Centre Oscar Lambret, Department of Clinical Research and Innovation, Lille, France ; 8 Lille University, CRIStAL UMR CNRS 9189, Lille, France Purpose or Objective The aim of this study was to assess, in a large series, the efficacy and tolerance of post-operative adjuvant hypofractionated stereotactic radiation therapy (HFSRT) for brain metastases (BMs). Material and Methods Between July 2012 and January 2017, 160 patients with 167 surgical cavities from 2 centers were operated for BM and treated by HFSRT. Patients had between 1-3 BMs, no brainstem lesion or carcinomatous meningitis. CT scan and gadolinium contrast-enhanced MRI were used for treatment planning. HFSRT was delivered using a CyberKnife®-type robotic accelerator.The primary endpoint was local control. Secondary endpoints were distant brain control, overall survival (OS) and tolerance to HFSRT. Results Seventy-three patients (46%) presented with non-small cell lung cancer (NSCLC), 23 (14%) had melanoma and 21 (13%) breast cancer. Median age was 58 years (range, 22- 83 years). BMs were synchronous in 50% of the cases. Median tumor size was 32 mm (range, 7-78 mm) and 75% of the cases (n=124) BMs were supratentorial. Planning MRI was performed in 151 patients (94%). The most frequent prescription regimens were 24 Gy in 3 fractions (n=52, 33%) and 30 Gy in 5 fractions (n=37, 23%). Local control rates at 6 months, 1 year and 2 years were

Yes

103 (36.5%) 1 (1.4%)

No

Resection status

Complete

17 (6%) 24

(33.8%) 39 (54.9%)

149 (52.8%)

Incomplete

n/a

13 (4.6%) 7 (9.9%)

Time resection - RT (median, 95% KI) [months] PET-imaging for RT planning

8.7 (19.8- 31.2)

3.8 (6.3- 16.3)

160 (56.7%) 122 (43.3%)

42 (59.2%) 29 (40.8%)

Yes

No

PET tracer

68Ga- Dotanoc/Dotatoc

68 (42.5%)

31 (73.8%)

23 (14.4%) 5 (11.9%) 69 (43.1%) 6 (14.3%)

F-18 FET

C11 Methionin

Results Median follow-up was 6.2 years (95%-KI: 6.6-7.6). For low- grade meningiomas, mean OS was 15.5 years (95%-KI: 14.7-16.2) and mean PFS was 15.2 years (95%-KI: 14.3- 16.0) (median was not reached); for high-grade cases median OS was 12.0 years (95%-KI: 3.8-20.2), and median PFS was 5.0 years (95%-KI: 2.4-7.6). PET imaging had was significant in OS (p=0.035) and PFS (p=0.044) for low-grade meningiomas; however, in the multivariate analysis, it remained only significant for PFS. For high-grade cases, PET had no influence.