Medical Health Encyclopedia

The use of helical CT for early screening is being debated. Studies of smokers who were given CT scans suggest that early screening will detect about 2% of lung cancers and most of these in early stages. In the studies, 62% to 82% of the patients with stage 1A cancer were still alive at five years. It should be noted, however, that neither study was controlled and the figures were likely to be higher than in actual practice.

Click the icon to see an image of a CT scan of the chest.

The evidence on survival benefits of early detection is not clear, however, and many experts are highly opposed to widespread screening for lung cancer. For example, some evidence suggests that non-small cell lung cancer cells are often highly aggressive at microscopic levels. If this is true, then the cancer would be highly likely to have already spread long before it was visible with CT scans. In fact, some studies have found no association between tumor size at the time of diagnosis and survival times. Conversely, some malignancies caught on CT scans may actually be very slow-growing nodules and so such patients might be more likely to die from aggressive treatments than from the cancer itself.

It should also be noted that about 98% of abnormalities seen on CT scans turn out to be benign. Even after rescreening, many scans will show suspicious areas that turn out to be harmless but will require invasive and expensive biopsies. Additional experience with CT scans, however, may allow experts to better determine which abnormalities are likely to be benign.

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High-risk individuals who are still interested in early screening with CT scans should ask their physician about available clinical trials.

Other Imaging Tests for Staging and Tracking Cancer

Computed tomography is the standard imaging procedure for determining if and where the cancer has spread (metastasized), for example to head, bone, or abdomen. Other imaging tests, however, may be useful for staging and tracking lung cancers.