AIM: PET/CT staging more effective for lung cancer, in most cases

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Image Source: Texas Cancer Center in Houston.

Preoperative staging with PET/CT and cranial imaging identified more patients with mediastinal and extrathoracic disease than conventional staging, thereby sparing more patients from stage-inappropriate surgery, but the strategy also incorrectly upstaged disease in more patients, according to a randomized trial in the Aug. 18 issue of the Annals of Internal Medicine.

Donna E. Maziak, MD, from the Ontario clinical oncology group at Hamilton Health Sciences, McMaster University in Hamilton, Ontario, and colleagues sought to assess whether whole-body PET/CT plus cranial imaging correctly upstages cancer in more patients with non-small cell lung cancer (NSCLC) than does conventional staging plus cranial imaging.

The researchers recruited patients from June 2004 to August 2007 in eight hospitals and five PET/CT centers in academic institutions. They stratified a centralized, computer-generated, variable block size randomization scheme by treatment center and cancer stage. Participants, healthcare providers and outcome assessors were not blinded to imaging modality assignment.

Eligible patients were older than 18 years; had histologic or cytologic proof of stage I, II or IIIA NSCLC on the basis of chest radiography and thoracic CT; and had a tumor considered to be resectable, according to the authors. All patients also had cranial imaging using CT or MRI.

Investigators assigned 170 patients to PET/CT and 167 to conventional staging. They found that eight patients (three who had PET/CT and five who had conventional staging) did not have planned surgery.

Maziak and colleagues reported that disease was correctly upstaged in 23 of 167 PET/CT recipients and 11 of 162 conventional staging recipients (13.8 vs. 6.8 percent), thereby sparing these patients from surgery. Disease was incorrectly upstaged in eight PET/CT recipients and one conventional staging recipient (4.8 vs. 0.6 percent), and it was incorrectly understaged in 25 and 48 patients, respectively (14.9 vs. 29.6 percent).

At three years, 52 patients who had PET/CT and 57 patients who had conventional staging had died, the researchers reported.

The authors acknowledged their limitations of a relatively small sample and the fact that some patients did not have planned surgery limited the ability to determine precise differences in clinical outcomes that were attributable to testing strategies.

Based on their findings, Maziak and colleagues concluded that a PET/CT-based imaging strategy may help identify advanced disease and prevent futile thoracotomy in patients with NSCLC, but it also has false-positive results that incorrectly upstage disease in some patients.

According to an accompanying editorial by Mitchell L. Margolis, MD, from the Philadelphia Veterans Affairs Medical Center and University of Pennsylvania in Philadelphia, said that “many issues remain, and it is particularly difficult to formulate recommendations for optimal preoperative assessment when the number of possible tests is increasing, along with important technical refinements in individual tests.”

Furthermore, Margolis questions whether CT or PET alone is now obsolete for staging lung cancer with the emergence of PET/CT; or are the advantages worth the increased (average) cost of $4,180 for PET/CT, compared to $3,060 for chest CT, $3,680 for PET; or how to incorporate new refinements in PET technology, such as dual-time-point imaging, into judgments about when to test and how to interpret the results.

However, he concludes “it is reasonable to order PET/CT for lung cancer staging, especially for patients who seem to be candidates for curative therapy. A recommendation to use PET/CT does not imply that other means of preoperative assessment are invalid or unacceptable; preferences among imperfect tests always depend on local expertise and test availability.”

Margolis added that additional comparisons between PET/CT and other staging tests—particularly studies that measure clinical outcomes and include cost analyses—are needed.