Lung cancer staging

Both CT and positron emission tomography (PET) can play an important role in the staging of lung cancer, and sometimes the visual correlation of CT and PET images is clinically useful. However, integrated PET-CT scanners have recently been introduced, and this technology appears to improve the accuracy of the staging of non-small-cell lung cancer.

Lardinois and associates studied 50 patients in whom non-small-cell lung cancer was documented or suspected. They compared the accuracy of integrated PET-CT, CT alone, PET alone, and conventional visual correlation of PET and CT. A tumor-node-metastasis stage was assigned on the basis of the image analysis. In 40 patients, the tumor stage was confirmed histologically. The nodal stage was confirmed histologically in 37.

Integrated PET-CT provided additional information in 20 (41%) of 49 patients. This additional information included the exact location of lymph nodes, precise evaluation of chest wall infiltration and of mediastinal invasion, correct differentiation between tumor and peritumoral inflammation or atelectasis, and exact location of distant metastasis (Figure).

[FIGURE OMITTED]

Integrated PET-CT had better diagnostic accuracy than the other imaging methods. With respect to tumor staging, integrated PET-CT was more accurate than CT alone, PET alone, or visual correlation of PET and CT. Node staging was more accurate with integrated PET CT than with PET alone. In metastasis staging, integrated PET-CT increased diagnostic certainty in 2 of 8 patients.

The authors acknowledge that the resolution of PET is not sufficient to detect the presence of microscopic lymph node metastases. If the radionuclide uptake is not increased on PET, integrated PET-CT should not be expected to provide further information.

Lardinois D, Weder W, Hany TF, et al, University of Zurich, Switzerland. Staging of non-small-cell lung cancer with integrated positron-emission tomography and computed tomography. N Engl J Med. June 19, 2003;348:2500-2507.