CT Monitoring of Lung Cancer Growth can be Unreliable, Study

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Digital radiography news According to a recent study, CT scans carried out to monitor lung cancer can be unreliable, leading to false results about the increase in the growth of cancer. The results of the study are discussed in the Journal of Clinical Oncology.

Gregory Riely, from Memorial Sloan-Kettering Cancer Center in New York, said "The patient and the doctor both need to understand that small changes don't necessarily mean much. Changes of up to 10 percent can happen simply as a result of the inherent variability of CT imaging."

The study took place at New York’s Memorial Sloan-Kettering Cancer Center. It involved 33 patients who were asked to undergo two chest CT scans within minutes. In general, doctors order CT scans for such patients once every few months to monitor the growth of the lung cancer. The indication of monitoring is also to evaluate the effect of medications and determine if there is a need to change them.

During the study, the research team sent the generated CT images to 3 radiologists to check them. These radiologists were not informed that the images came from 2 successive CT scans. Yet, they said that there were many changes between the 2 scans. The reported changes ranged from 23% decrease in tumor size until 31% increase in its growth.

Dr. Riely said that various doctors would start treatment procedures following detection of small changes on CT scans, which can be inappropriate, as indicated by this study. Dr. Riely explained "We begin to put more and more stock in the data without really understanding the true variability of those measurements. The changes are not clinically meaningful and we should not alter clinical care based on them."

Meanwhile, Dr. Riely said that the result of this study do not mean that patients should undergo more CT scans, as this means additional un-wanted radiation exposure. He also added that the indication of the study extends to other conditions in addition to lung cancer. He noted that imaging procedures on chest can show variables due to the breathing movement.

Michael Maitland, from the University of Chicago, said that the study is highly useful and he was surprised that it has not been conducted before. He explained "This is telling us scientifically how much noise is naturally there without any treatment or the cancer getting worse. It's an important thing to do whenever you are going to use any kind of marker for a disease."

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