|
|
[18F]Fluorodeoxyglucose PET-CT and Lung Cancer: A Significant Referral Bias Exists
I. C. Okereke, S. Gangadharan, M. Kent, M. DeCamp*. Beth Israel Deaconess Medical Center, Boston, MA,
BACKGROUND:
[18F]Fluorodeoxyglucose PET-CT scan is a tool widely used in the diagnosis and staging of lung cancer. Referral bias is present when the results of a diagnostic study affect the decision to proceed with definitive testing. This bias artificially increases the sensitivity and decreases the specificity. The accuracy of PET-CT scan in suspected lung cancer and the role of referral bias were investigated.
METHODS:
From January 2005 through June 2007, 585 consecutive patients undergoing PET-CT scan for suspected lung cancer were studied. Endpoints measured included qualitative and quantitative results of PET-CT scans and pathologic results from patients who underwent invasive procedures for diagnosis, staging and/or therapy. A positive PET scan was defined as one in which the SUV was greater than 2.5. A standard mathematical model, based on overall results of PET-CT scan in all patients, was used to create adjustments to account for the effect of referral bias.
RESULTS:
413 (71%) of PET-CT scans were reported as positive, while 172 (29%) were negative. Attempt at tissue diagnosis occurred in 417 patients (71%); surgical intervention was performed in 246 (42%). Whereas 86% (354/413) of patients with a positive PET-CT scan underwent tissue sampling, only 36% (62/172) with a negative PET-CT scan had an attempt (p<.001). In patients with a positive study, a higher SUV was associated with an attempt at tissue diagnosis (p<.001). Before adjustment, the sensitivity and specificity of PET-CT scan for any cancer were 87% and 43%. After adjustment, sensitivity fell to 80%, while specificity rose to 57%. The unadjusted sensitivity of PET-CT scan for detecting mediastinal disease was only 79%.
CONCLUSIONS:
The accuracy of PET-CT scan is significantly influenced by referral bias, and a strong reliance is placed on its results. Furthermore, patients with a positive PET-CT scan are more likely to undergo tissue sampling as the SUV increases. Given the relatively low sensitivity of PET-CT scan in detecting disease and its poor performance in the mediastinum, PET-CT scan may have too high an impact on the decision to undergo further invasive diagnostic procedures. Patients should not be deferred from tissue sampling based solely on a negative PET-CT scan.
Any Cancer | Sensitivity | Specificity | PPV | NPV | | Unadjusted (%) | 87 | 43 | 86 | 46 | | Adjusted (%) | 80 | 57 | N/A | N/A |
Back to 2008 Annual Meeting
Back to Program Outline
|
