PET/CT in cancer: moderate sample sizes may suffice to justify replacement of a regional gold standard.
OBJECTIVE
For certain cancer indications, the current patient evaluation strategy is a perfect but locally restricted gold standard procedure. If positron emission tomography/computed tomography (PET/CT) can be shown to be reliable within the gold standard region and if it can be argued that PET/CT also performs well in adjacent areas, then sample sizes in accuracy studies can be reduced.


METHODS
Traditional standard power calculations for demonstrating sensitivities of both 80% and 90% are shown. The argument is then described in general terms and demonstrated by an ongoing study of metastasized prostate cancer.


RESULTS
An added value in accuracy of PET/CT in adjacent areas can outweigh a downsized target level of accuracy in the gold standard region, justifying smaller sample sizes.


CONCLUSIONS
If PET/CT provides an accuracy benefit in adjacent regions, then sample sizes can be reduced and the conduct of trials accelerated, leading to earlier decisions on the use of PET/CT while exposing fewer patients and reducing overall costs.
Department of Nuclear Medicine, Odense University Hospital, Odense C, Denmark. oke@stat.sdu.dk
Oke
O
Gerke
Mads Hvid
MH
Poulsen
Kirsten
K
Bouchelouche
Poul Flemming
PF
Høilund-Carlsen
Werner
W
Vach
D002986:Clinical Trials as Topic; D006801:Humans; D008297:Male; D049268:Positron-Emission Tomography / Q000379:methods*; D011471:Prostatic Neoplasms / Q000175:diagnosis*; D018401:Sample Size; D012680:Sensitivity and Specificity; D014055:Tomography, Emission-Computed / Q000379:methods*