Cancer Screening with Whole-body PET/CT for Healthy Asymptomatic People in Japan : Re-evaluation of its Test Validity and Radiation Exposure

The use of Positron Emission Tomography (PET) or PET/CT for voluntary cancer screening of asymptomaticindividuals is becoming common in Japan, though the utility of such screening is still controversial. This studyestimated the general test validity and effective radiation dose for PET/CT cancer screening of healthy Japanesepeople by evaluating four standard indices (sensitivity, specificity, positive/negative predictive values), andpredictive values with including prevalence for published literature and simulation-based Japanese data. CTand FDG-related dosage data were gathered from the literature and then extrapolated to the scan parameters ata model PET center. We estimated that the positive predictive value was only 3.3% in the use of PET/CT forvoluntary cancer screening of asymptomatic Japanese individuals aged 50-59 years old, whose average cancerprevalence was 0.5%. The total effective radiation dose of a single whole-body PET/CT scan was estimated to be6.34 to 9.48 mSv for the average Japanese individual, at 60kg body weight. With PET/CT cancer screening inJapan, many healthy volunteers screened as false positive are exposed to at least 6.34 mSv without getting anyreal benefit. More evaluation concerning the justification of applying PET/CT for healthy people is necessary.