Overdiagnosis occurring in low-dose CT screening for lung cancer

More than 18 percent of all lung cancers detected with low-dose CT screening (LDCT) are overdiagnosed, according to a study published by JAMA Internal Medicine on Dec. 9.

While LDCT has been proven to effectively screen some patients, a percentage of the tumors found during screening are indolent or clinically insignificant.

“Overdiagnosis is one of the limitations of screening because it incurs unnecessary treatment, morbidity (and mortality in rare cases), follow-up, cost, and anxiety and labels a patient with a disease that otherwise would never have been detected,” wrote the study’s lead author Edward F. Patz Jr., MD, of Duke University Medical Center in Durham, N.C.

Patz and colleagues estimated overdiagnosis in LDCT by analyzing data from the National Lung Screening Trial, which compared LDCT screening versus chest radiography (CXR) in 53,452 people at high risk for lung cancer.

Of the 1,089 cancers reported in the LDCT group during follow-up, the researchers estimated that 18.5 percent were overdiagnosed. They additionally estimated that 22.5 percent of non-small cell lung cancer detected by LDCT were overdiagnosed, and that 78.9 percent of bronchioalveolar lung cancers detected by LDCT represented an overdiagnosis.

“In the future, once there are better biomarkers and imaging techniques to predict which individuals with a diagnosis of lung cancer will have more or less aggressive disease, treatment options can be optimized, and a mass screening program can become more valuable,” surmised the study’s authors.