CT Tumor Measure Changes Not Indicative of Progression

Lung tumor reimaging within 15 minutes shows diameter change without disease progression

FRIDAY, July 8 (HealthDay News) -- There is a clinically important magnitude of tumor measurement variability inherent in repeat computed tomography (CT) imaging, especially for small tumors, which may not be indicative of tumor progression, according to a study published online July 5 in the Journal of Clinical Oncology.

Geoffrey R. Oxnard, M.D., from the Weill Cornell Medical College in New York City, and colleagues investigated the clinical implications of variable lung tumor measurements attained by repeat CT scans performed within 15 minutes of each other in 30 patients with non-small-cell lung cancer (NSCLC) and target lung lesions of one or more centimeters in diameter. The tumor diameter differences in scans were compared in a side-by-side fashion by three experienced radiologists.

The investigators found that 57 and 33 percent of measurements exceeded 1 and 2 mm in diameter, respectively. Tumor measurements ranged from 23 percent shrinkage to 31 percent growth (average increase and decrease of +4.3 and −4.2 percent, respectively). According to the response evaluation criteria in solid tumors (RECIST; ≥20 percent increase), 3 percent of the measurements met the progression criteria, while 84 percent of the measurements had increases and decreases within 10 percent. Percent measurement change showed significantly greater variability in smaller lesions.

"This rescan study of lung lesions in patients with advanced NSCLC found a clinically important magnitude of measurement variability inherent in repeat CT imaging. This variability is greatest in the measurement of small tumors and has important implications for accurate determination of disease progression," the authors write.

One of the study authors disclosed financial ties to the pharmaceutical industry.

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Physician's Briefing

Published on July 08, 2011

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