Early FDG-PET and Volumetric Analysis May Be Best Predictors of Benefit in Ewing Sarcoma

Key Points

  • FDG-PET was better than anatomic imaging in identification of response in patients with Ewing sarcoma.
  • Among anatomic imaging criteria, volume analysis identified the most responders.

In a study reported in the Journal of Clinical Oncology, Koshkin et al found that among anatomic and functional imaging modalities, volumetric analysis and outcome with early 18F-fluorodeoxyglucose (FDG)–positron-emission tomography (PET) were the best predictors of benefit in patients with Ewing sarcoma.

Study Details

The study involved comparison of imaging methods and local vs central reading among 89 evaluable patients enrolled in a trial of an IGF1R antibody in Ewing sarcoma, including PET Response Criteria in Solid Tumors (PERCIST) for functional imaging and World Health Organization (WHO) criteria performed locally and centrally, RECIST, and volumetric analysis for anatomic imaging.

Functional and Anatomic Imaging

On volume analysis, disease progression defined as a cumulative lesion volume increase of 100% at 6 weeks was the optimal cutoff for decreased overall survival (P < .001). Disease progression on the day-9 FDG-PET scan predicted reduced overall survival in progressors vs nonprogressors (P = .001) and improved overall survival in responders vs nonresponders.

PERCIST identified more patients with response (43.9%) compared with volume criteria (25%), WHO central (22.4%), WHO local (18.4%), or RECIST (21.1%) criteria. PERCIST identified more patients with response or stable disease (90.9%), compared with volume criteria (64.5%), RECIST (55%), WHO central (51%), and WHO local (50%). Fewer patients were identified as having progressive disease by functional imaging vs anatomic imaging; PERCIST classified 12% with progressive disease, compared with 36% by volumetric analysis, 45% by RECIST, 49% by WHO central, and 50% by WHO local criteria.

The investigators concluded: “An early signal with FDG-PET on day 9 and volume analysis were the best predictors of benefit. Validation of the volumetric analysis is required.”

The study was supported by the Radiological Society of North America, Quantitative Imaging Biomarker Alliance, Sarcoma Alliance for Research Through Collaboration, National Cancer Institute, and National Institutes of Health.

Laurence H. Baker, DO, of the University of Michigan Medical School, is the corresponding author of the Journal of Clinical Oncology article.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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