Value of CT scan for lung cancer questioned

Doctors these days may recommend a CT scan for people who smoke or have other risk factors for lung cancer. The CT scan can spot lung nodules at an earlier stage than can chest x-rays or other tests. However, so far, studies have not shown that such screening actually reduces lung cancer deaths.

"Finding a lung cancer when it is small does not necessarily mean the cancer is at an earlier stage of development," lead investigator Dr. Edward F. Patz from Duke University in Durham, North Carolina, notes in a statement.

"The genetic characteristics of a tumor likely dictate its behavior more than its size. Smaller lung tumors can represent late-stage lung cancer," he adds.

Patz and colleagues used data from two big studies to estimate lung cancer mortality among individuals at high risk for lung cancer who were screened using low-dose CT. These estimates were then compared with those from the Mayo Lung Project, which used chest x-rays and sputum testing to screen high-risk individuals.

The mortality estimate from the two CT studies was between 4.1 and 5.5 lung cancer deaths among the equivalent of 1000 people every year, which is very similar to the 3.9 to 4.4 deaths in the Mayo Lung Project, which did not use CT screening.

These results are "indeed sobering," the authors write in the Journal of Clinical Oncology.

"At this time, given the expense and potential risks, though small, of CT screening - and without additional data to demonstrate that this screening method actually saves patient lives - mass screening for the general population can not be recommended," Patz comments.

The results of a randomized trial now in progress comparing CT screening with chest radiographs are needed to determine "the true utility of mass screening with CT for lung cancer," Patz's team concludes.

SOURCE: Journal of Clinical Oncology, June 1, 2004.