Image-based response assessment of liver metastases following stereotactic body radiotherapy with respiratory tracking.
OBJECTIVE
To describe post-CyberKnife® imaging characteristics of liver metastases as an aid in assessing response to treatment, and a novel set of combined criteria (CC) as an alternative to response according to change in size (RECIST).


METHODS
Imaging data and medical records of 28 patients with 40 liver metastases treated with stereotactic body radiotherapy (SBRT) were reviewed. Tumor size, CT attenuation coefficient, and contrast enhancement of lesions were evaluated up to 2 years post SBRT. Rates of local control, progression-free survival, time to progression, and overall survival according to RECIST and CC were estimated.


RESULTS
Complete response (CR) was 3.6% (95% CI: 0.1-18%) and 18% (95% CI: 6-37%) according to RECIST and combined criteria, respectively. Two progressive diseases and two partial responses according to RECIST were classified as CR by the combined criteria and one stable response according to RECIST was classified as progressive by CC (Stuart-Maxwell test, p = 0.012). The disease control rate was 60.7% (95% CI: 41-78%) by RECIST and 64% (95% CI: 44%-81%) by CC.


CONCLUSIONS
Use of response criteria based on change in size alone in the interpretation of liver response to SBRT may be inadequate. We propose a simple algorithm with a combination of criteria to better assess tumor response. Further studies are needed to confirm their validity.
Department of Radiology, CLCC Oscar Lambret, 3 rue Frédéric Combemale, BP 307, Lille cedex, 59020, France. h-jarraya@o-lambret.fr
Hajer
H
Jarraya
Xavier
X
Mirabel
Sophie
S
Taieb
Sylvain
S
Dewas
Emmanuelle
E
Tresch
Francois
F
Bonodeau
Antoine
A
Adenis
Andrew
A
Kramar
Eric
E
Lartigau
Luc
L
Ceugnart
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D016634:Radiosurgery / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods; D016896:Treatment Outcome; D055815:Young Adult