Researchers from Canada have reported that preoperative whole-body positron emission tomography, computed tomography (PET-CT), and cranial imaging identifies more patients with mediastinal and extrathoracic non–small cell lung cancer (NSCLC) than conventional staging. However, some patients were upstaged incorrectly by PET-CT. The details of this study were reported in the August 16, 2009 issue of the Annals of Internal Medicine.[1]

Computerized tomography (CT) and positron-emission tomography (PET) are important diagnostic techniques for staging of patients with NSCLC. However, each technique has limitations. A combined PET-CT machine has been developed and has undergone limited evaluation. The integrated PET-CT machine combines the structural information obtained by CT with the metabolic information obtained by PET into one set of images. One advantage of this approach is that small lesions detected with PET can be more precisely located using CT. Another potential advantage is that PET-CT will detect patients with metastatic disease and reduce the number of thoracotomies performed. For example, researchers from Denmark have recently reported: “The use of PET-CT for preoperative staging of NSCLC reduced both the total number of thoracotomies and the number of futile thoracotomies but did not affect overall mortality.”

The current study was a randomized trial in 337 patients with Stage I-IIIA NSCLC. Patients were randomly allocated to be staged with PET-CT or conventional staging with an abdominal CT and a bone scan. Patients in both groups had cranial examinations with CT or MRI. Extent of disease was correctly upstaged in 13.8% of patients in the PET-CT group and 6.8% of conventionally staged patients. Upstaged patients were spared a thoracotomy. Extent of disease was incorrectly upstaged in 4.8% of PET-CT patients versus 0.6% of conventionally staged patients. PET-CT understaged 14.9% of patients versus 29.6% for conventional staging. At three years a similar number of patients had died in both groups. These authors concluded that PET-CT could accurately upstage some patients who could avoid thoractomy. However, some patients would be falsely upstaged by this technique.

Comments: It would appear that more patients benefit from upstaging by not having a thoracotomy than are harmed by overstaging; this would deny these patients a thoracotomy and make PET-CT a useful staging test for NSCLC. These results combined with data from other studies suggest that PET-CT has no impact on survival of patients with NSCLC.

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