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Letter to the Editor
PET–CT in lung cancer: data discrepancies
  1. Jose M Paredes1,
  2. Jayesh Mehta2
  1. 1University of Illinois, Chicago, Illinois, USA
  2. 2Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA
  1. Correspondence to Jayesh Mehta, Northwestern University, Feinberg School of Medicine, 676 N Saint Clair St, Suite 850, Chicago, Illinois 60611, USA; j-mehta{at}

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The Danish study of positron emission tomography (PET)–CT versus conventional staging (CS) in non-small cell lung cancer has been reported twice now1 2 and corrected once.3

However, there are discrepancies in numbers between the manuscripts,1 2 which is surprising given the small number of patients (n=189) and centres (n=3). Was endoscopic ultrasonography done in 42 or 47 of 98 PET–CT patients, and in 30 or 35 of 91 CS patients? Was fine-needle aspiration done in 36 or 40 PET–CT patients, and in 24 or 29 CS patients?2 Was fine-needle aspiration positive in 16 or 19 PET–CT patients? Was mediastinoscopy positive in 10 or 12 CS patients? Can the authors explain the discrepancies and show how any reconciliation of the numbers affects the findings of each manuscript?

While the total downstaging in both groups was comparable (62% vs 71%, p=0.19), the implied downstaging in the PET–CT arm as a result of modalities other than PET–CT was significantly lower (41% vs 71%; p=0.001). One would have expected the proportion of patients experiencing downstaging based on non-PET–CT investigations to be similar in both groups in a randomised study. It is possible that the apparent superiority of PET–CT is simply the result of inadequacy of non-PET–CT investigations in the CS arm.

Our concern is that the conclusions in both manuscripts have hinged upon small differences in the PET–CT and CS groups, which could simply be due to analytical errors or technical deficiencies of the sort described above. We respectfully suggest that the accuracy of the primary data from this important study be verified independently by the journals.


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  • Competing interests None.

  • Provenance and peer review Not commissioned; internally peer reviewed.

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