Abstract A24: Diagnostic performance of PET and PET/CT for cancer detection in asymptomatic volunteers
Authors: Chung Ji In , Cho HanByoul , Shim Jae-Yong , Choi Joon Young , Lee Kyung-Han , Kim Byung-Tae , Choi Yoon-Ho 
Published: May 2012

Abstract
Purpose: We investigated retrospectively the diagnostic performance of 18F-fluorodeoxyglucose positron emission tomography (PET) and PET/CT for cancer detection in asymptomatic volunteers.
Materials and Methods: This study consisted of 5091 whole-body PET or PET/CT underwent as a part of annual health check-up at one hospital from 1998 to 2008. Annual health check-up program of the hospital includes comprehensive blood tests, urinalysis, stool examination, chest X-ray, mammography, abdominal sonography, and gastrofiberscopy. Lung CT, brain MRI, breast sonography, thyroid sonography, or colonoscopy were performed in some individuals. To find the incidence of cancers, medical records of the subjects were thoroughly reviewed for a follow-up period of one year. Cases with cancer detected before PET or PET/CT scanning were excluded. The pattern of formal readings of PET and PET/CT were analyzed to assess the sensitivity and specificity for cancer detection. The stage and histopathology of the cancers were evaluated in relation to detection or missing by PET.
Results: Eighty-six cancers (1.7%, 86/5091) were diagnosed within one year after PET or PET/CT. Sixty-nine (1.5%, 69/4503) cancers were detected in men and 17 (2.9%, 17/588) cancers were detected in women. They included 33 thyroid cancers, 10 prostate cancers, 9 stomach cancers, 9 colorectal cancers, 7 lung cancers, and other cancers. PET and PET/CT in combination had a sensitivity of 53.5% (46/86) and a specificity of 81.1% (4061/5005) for cancer detection. Positive predictive value was 4.6% (46/990) and negative predictive value was 99.0% (4061/4101). PET only had a sensitivity of 51.3% (40/78) and a specificity of 81.4% (3625/4452), and PET/CT only had a sensitivity of 75.0% (6/8) and a specificity of 78.8% (436/553) respectively. A total of 44 PET negative cancers (little FDG uptake) include 13 thyroid cancers, 7 prostate cancers, 7 colorectal cancers, 4 stomach cancers, and others. When comparing tumor stages, early cancers (stage 0 or 1) comprised 59% (26/44) of PET negative cancers, and 40% (17/42) of PET positive cancers. However, there were no statistically significant differences in cancer site, stage and histopathology between PET positive cancers and PET negative cancers. In 19.3% of formal readings of PET and PET/CT, further evaluation was recommended to exclude malignancy or significant disease. Commonly recommended sites for further evaluation were head and neck, upper gastrointestinal tract, thyroid, lung and mediastinum, and lymph nodes. Diagnostic modalities recommended for further evaluation were physical examination, esophagogastroduodenoscopy, CT, biopsy, and others.
Conclusions: PET and PET/CT showed a moderate performance for detecting cancers in asymptomatic adults in this study. More experience and further investigation are needed to overcome limitations of PET and PET/CT for cancer screening.
Citation Information: Cancer Prev Res 2010;3(1 Suppl):A24.