CT scans for lung cancer may be unreliable

CT scans are used to measure and determine treatment for lung tumors. However, they can be unreliable, potentially leading patients and their doctors to believe lung cancer is progressing when it’s not.

“The patient and the doctor both need to understand that small changes don’t necessarily mean much,” Dr. Gregory Riely, a lung cancer specialist at Memorial Sloan-Kettering Cancer Center in New York. “Changes of up to 10 percent can happen simply as a result of the inherent variability of CT imaging.”

Riely’s study is the first to measure the accuracy of the CT scan for this purpose. Which is amazing since its use has taken off and become the go-to for lung cancer treatment.

For this test they asked advance stage lung cancer patients if they would have two scans done in rapid succession. According to objective analysis, many of the same tumors were identified as having changed, as much as 31% in the few minutes between scans. Overall three percent appeared to have grown so much that doctors would have diagnosed disease progression and advised more aggressive treatment.

“We begin to put more and more stock in the data without really understanding the true variability of those measurements,” he said. “Small changes are not clinically meaningful and we should not alter clinical care based on them.” The doctors are hoping to build better models of the disease progression so that better treatment can be provided.

Source: Journal of Clinical Oncology, Reuters