Participants in the Mayo Lung Project who had been previously diagnosed with lung cancer were interviewed about their diagnosis, overall health, and smoking history. Researchers also reviewed the results of the patients' chest scans. Patients were divided into two groups -- one where patients were screened with multiple chest X-rays, and one where spectrum tests were used.
Of the 7,118 patients studied, 585 in the X-ray group were identified as having cancer, and 500 were identified in the spectrum test group. The researchers said the additional cancers identified in the X-ray group point to an overdiagnosis of lung cancer.
"Although the magnitude of overdiagnosis in chest X-ray screening appears to be modest, the very real and deleterious role that overdiagnosis plays in mass screening cannot be discounted," Pamela M. Marcus, a researcher with the National Cancer Institute, said in a prepared statement. "The newest imaging technologies can detect very small lung abnormalities, but these abnormalities may be clinically unimportant. The question remains as to whether early detection of lung cancer through mass screening results in a net benefit to the public's health."
Overdiagnosis can lead to unnecessary tests and treatment of a disease that may result in exposure to harmful toxins, the researchers said.
The study results appear in the June 7 issue of the Journal of the National Cancer Institute.