A disheartening new study published this week in the Journal of the American Medical Association (JAMA) has found that lung-cancer screening done by CT scans has not had the life-saving benefits it was believed to have. In addition, use of CT scans may lead to unnecessary and potentially dangerous medical procedures.
“Screening for lung cancer with low-dose CT may increase the rate of lung cancer diagnosis and treatment, but may not meaningfully reduce the risk of advanced lung cancer or death from lung cancer,†the study’s authors conclude.
The new research, led by Dr. Peter Bach of Memorial Sloan-Kettering Cancer Center in New York, was based on three single-arm studies with a combined cohort of 3246 participants. The studies were from the Instituto Tumori in Milan, Italy, the Mayo Clinic in Rochester, Minn., and the Moffitt Cancer Center in Tampa, Fla.
CT, or computed tomography, scans were hoped to be an improvement over chest X-ray screening. Chest x-rays increased the detection rate of small (or resectable) lung cancers and therefore the frequency of lung surgery, but it did not reduce the risk of either advanced lung cancer or death from lung cancer. However, the authors of the new study found that CT scans did not ultimately address this issue either.
“In our study of CT screening,†they write, “we observed a similar pattern. When individuals are screened for lung cancer with CT, the likelihood that they are diagnosed with lung cancer is increased more than threefold, and the likelihood that they undergo a thoracic resection for lung cancer is increased tenfold. However, as for chest x-ray screening, there appears to be neither a meaningful reduction in the number of advanced cancers being diagnosed nor a reduction in the number of individuals who die of lung cancer. These findings, because they are thematically consistent with the findings of several randomized studies of lung-cancer screening with chest x-ray, should raise doubts about the premise underpinning CT screening for lung cancer, and also raise concerns about its potential harms if pursued on a wide scale.â€Â
The authors note that lung-cancer screening by both CT scans and chest X-ray depends on the same “unproven†premise: “that most cases of lung cancer that will cause death can be detected through routine screening while they are still localized and potentially curable.†In the end, the authors write, “CT screening for lung cancer should be considered an experimental procedure, based on an uncorroborated premise.â€Â
Currently, the National Cancer Institute is undertaking a study of more than 50,000 individuals to determine the effectiveness of CT scans, and that study is expected to provide the most conclusive evidence yet. However, the results of that study won’t be known for a few more years. At this point, even the American Cancer Society does not recommend widespread CT scan screening.
