Dr. Peter B. Bach from Memorial Sloan-Kettering Cancer Center in New York and his colleagues from other institutions have investigated whether low-dose CT screening would increase the number of lung cancer diagnoses, therefore reducing the risk of advanced lung cancer.

Previous studies of lung cancer screening with chest x-rays have shown that, although x-rays can identify small tumors that can be removed, they do not reduce the number of advanced lung cancer diagnoses and deaths. As reported in the March issue of JAMA, the researchers wanted to see whether CT screening — which is even more sensitive for detecting small nodules — might produce more hopeful results.

Annual CT scans were performed on 3246 current or former smokers for about 3.9 years at three academic medical centers — two in the US and one in Italy. The patients received scans for three to four years.

There were several more diagnoses of lung cancer than would have occurred without the CT screening — 144 diagnosed compared with an expected 44.5. And of those 144, 109 patients received surgical treatment, as compared with an expected 10.9 cases of surgery. However, there was no evidence that the screening reduced the number of diagnoses of advanced lung cancers or deaths — similar results to the chest x-ray screening studies.

The researchers believe that further study is needed on CT screening and on other imaging modalities. Until there is more evidence, they believe that CT screening should be considered experimental.