Caution Re: Apparent Cancer Progression

In the August 10, 2011 issue of the Journal of Clinical Oncology, authors from Memorial Sloan-Kettering published a simple and provocative study (abstract). Lung tumour nodules were measured on CT scan, then patients were rescanned just fifteen minutes later and the nodules remeasured.

The main findings: differences in nodule measurements in excess of 1 and 2 mm were common (57% and 33%, respectively). Most significant is the risk of misdiagnosing progression. RECIST criteria for progression (>=20% increase) were met in 3% of these cases, about 1 in 30.

Oncologists need to keep these findings in mind when evaluating small serial changes in tumour measurement, and when making decisions about initiating or abandoning treatment.

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