Clinical value of 18F-FDG-PET/CT in suspected serious disease with special emphasis on occult cancer
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Suspected serious disease (SSD) is a disease designation often given to patients with one or more non-specific symptoms of severe disease that could be due to cancer; the optimal diagnostic strategy is largely left to the clinician’s discretion. Being a sensitive non-invasive whole-body imaging modality 18F-FDG-PET/CT may have a potential role in this cancer-prevalent group of patients to confirm or refute suspected malignancy. We aimed to investigate the diagnostic value of 18F-FDG-PET/CT in SSD using long-term follow-up as reference.
We retrospectively studied results obtained in all SSD patients referred for 18F-FDG-PET/CT at a single institution in 2010–2011 retrieving the following clinical data in all patients: journal entries, examinations, and evaluations made from 6 months before the scan and until the latest recorded entry. A true positive PET scan was a positive scan with a subsequently biopsy-confirmed diagnosis of cancer in the same target organ, whereas a false positive scan had no subsequent cancer diagnosis. A true negative PET scan was a negative scan without a cancer diagnosis during follow-up, whereas a false negative PET scan was one with a subsequently confirmed cancer diagnosis.
Ninety-three patients, aged 67 years (range 25–89) were included and followed for up to 7.3 years (median 6). Of these, 21 [22.6% (95% CI 15.3–32.1)] turned out to have cancer. With 18F-FDG-PET/CT, the sensitivity was 81.0% (95% CI 60.0–92.3), specificity 76.4% (95% CI 65.4–84.7), positive predictive value 50% (95% CI 34.1–65.9), and negative predictive value 93.2% (95% CI 83.8–97.3). Five patients with negative scans were subsequently diagnosed with cancer.
Cancer prevalence is substantial among patients with SSD. 18F-FDG-PET/CT is a promising option in this setting, in particular because a high negative predictive value equals a low incidence of cancer during follow-up. Further studies are needed to establish the role of 18F-FDG-PET/CT in SSD.
KeywordsOccult cancer Suspected serious disease FDG PET/CT
The authors acknowledge Eivind Antonsen Segtnan, BSc., PhD candidate, for guidance, advice, and moral support, and the secretary Bente Stillingsborg for invaluable help with data retrieval.
There are no financial disclosures; this work received no funding.
Compliance with ethical standards
Conflict of interest
All authors declare that they have no conflicts of interest.
Human and animal rights
This article does not contain any studies with human participants or animals performed by any of the authors; only retrospective data was included.
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