PET for Unknown Primary Site, Occult Primary – pro
Lay Summary: PET and PET/CT are useful to the find primary site of metastases when it is not known.
FDG-PET is useful to detect the primary tumor in patients with unknown primary tumors, according to a recent meta-analysis, which suggests that PET’s intermediate specificity, high sensitivity, and concomitant low false-negative rate offer substantial benefits in the initial stages of oncologic patient management.
Survival is low for patients with unknown primary tumors: less than six months from the time of initial diagnosis, and 11% and 6% at three-year and five-year follow-up, respectively.
At initial diagnosis, unknown primary tumors occur between 0.5% and 7% of oncologic cases. At follow-up, the prevalence is between 3% and 15%. Also, unknown primary tumors have no specific metastatic location. The meta-analysis of the literature found F-18 FDG-PET detected the primary tumor in 43% of 298 patients with unknown primary tumors. Sensitivity and specificity were 87% and 71%, respectively. Researchers also analyzed 15 studies that met the inclusion criteria.
FDG-PET is useful to detect the primary tumor in patients with unknown primary tumors, according to a recent meta-analysis, which suggests that PET’s intermediate specificity, high sensitivity, and concomitant low false-negative rate offer substantial benefits in the initial stages of oncologic patient management. Howeer, its role in restaging is nto etablished.
Survival is low for patients with unknown primary tumors: less than six months from the time of initial diagnosis, and 11% and 6% at three-year and five-year follow-up, respectively.
Value of restaging PET had not been established defintievley for patients on treatment of occult primary cancer.
Regelink G, Brouwer J, De Bree R, et al. Detection of unknown primary tumors and distant metastases in patients with cervical metastases: value of FDG-PET versus conventional modalities. Eur J Nucl Med 2002;29:1024-1030.
Reske SN, Kotzerke J. FDG-PET for clinical use. Results of the 3 rd German Interdisciplinary Consensus Conference. Eur J Nucl Med 2001;28:1707-1723.
nccn.org. occult primary, 2018 OCC-3
Ahmed MohamedWafaie et al, Cancer of unknown primary origin: Can FDG PET/CT have a role in detecting the site of primary?The Egyptian Journal of Radiology and Nuclear Medicine. Volume 49, Issue 1, March 2018, Pages 190-195
nccn.org. occult primary OCC-3
Lebech AM et al, Whole-Body 18F-FDG PET/CT Is Superior to CT as First-Line Diagnostic Imaging in Patients Referred with Serious Nonspecific Symptoms or Signs of Cancer: A Randomized Prospective Study of 200 Patients.J Nucl Med. 2017 Jul;58(7):1058-1064