In his blog, Dr. Mercola wrote: http://articles.mercola.com/sites/articles/archive/2011/08/06/lung-cancer-scans-can-be-unreliable.aspx?e_cid=20110806_DNL_art_2
It’s important to understand that many medical procedures are not an exact science, and this includes CT scans used to measure cancer growth. In the case of CT scans for lung cancer, this new study showed that radiologists reviewing images of the same patient taken just minutes apart found substantial “changes” in the tumors, in some cases noting they had gotten up to 31 percent bigger or 23 percent smaller.
And in about 3 percent of the cases, the “growth” appeared significant enough that disease progression would be diagnosed, which would undoubtedly impact the person’s future course of treatment, not to mention their state of mind.
Reference J Clin Oncol. 2011 Jul 5. [Epub ahead of print]
Variability of Lung Tumor Measurements on Repeat Computed Tomography Scans Taken Within 15 Minutes.
Memorial Sloan-Kettering Cancer Center, Weill Cornell Medical College, New York, NY.
Patients with non-small-cell lung cancer and a target lung lesion ≥ 1 cm consented to undergo two CT scans within a period of minutes. Three experienced radiologists measured the diameter of the target lesion on the two scans in a side-by-side fashion, and differences were compared.
- Apparent changes in tumor diameter exceeding 1 to 2 mm are common on immediate reimaging. Increases and decreases less than 10% can be a result of the inherent variability of reimaging.
- Caution should be exercised in interpreting the significance of small changes in lesion size in the care of individual patients and in the interpretation of clinical trial results.