Value of FDG PET/CT in patients with treated ovarian cancer and raised CA125 serum levels.
OBJECTIVE
Patients treated for ovarian cancer are usually referred for 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography (FDG PET/CT) in case of increased Carcinoma Antigen 125 (CA125) but negative conventional imaging. However, there is not enough in the literature to support the value of FDG PET/CT in this context. This study aimed to assess role of FDG PET/CT in a cohort of patients with treated ovarian cancer and correlate the results with serum levels of CA125.


METHODS
We retrospectively studied 175 patients, mean age 65.2 years (range 24-88 years) who had radical treatment for ovarian cancer (chemotherapy, surgery or combination). The patients had a standard FDG PET/CT and measurement of serum CA125 within a month of the scan. PET/CT was considered positive if demonstrated areas of abnormally increased metabolic activity unrelated to physiological distribution, on the basis of a visual analysis. The results of PET/CT imaging were compared to the level of CA125, and receiver operating characteristic (ROC) curves were plotted and area-under-the curve (AUC) statistics were computed. Cytologic or histologic data or clinical and imaging follow-up were taken as gold standard.


RESULTS
Patients were divided into five groups based on CA125 values. The average level of CA125 was 107.7 (range 3-867, SD 166.1). PET/CT was positive in 125/175 cases (71.4%), mean value of CA125 132.2 (SD 182.9) and negative in 50/175 (28.6%), mean value of CA125 46.4 (SD 89.3). In descriptive ROC analyses, the discriminatory power of this marker was relatively high (AUC statistics 0.77, range = 0.703-0.8). The optimal cut-off point of CA125 after treatment to reflect active disease on PET/CT was 18 U/mL achieving a detection rate of 85.6%. There was no relation between PET/CT negativity and the histological type of the tumor.


CONCLUSIONS
PET/CT was able to detect active disease at relatively low levels of CA125, thereby facilitating the early diagnosis of recurrence or residual disease. Also in patients with low CA125 levels (<30), PET/CT had a relatively high detection rate (53%). According to our preliminary results, the use of FDG PET/CT in this setting is justified even with low serum CA125 levels.
Department of Nuclear Medicine, Hospital General Ciudad Real, Ciudad Real, Spain.
Azahara
A
Palomar
Cristina
C
Nanni
Paolo
P
Castellucci
Valentina
V
Ambrosini
Gian Carlo
GC
Montini
Vincenzo
V
Allegri
Cinzia
C
Pettinato
Adil
A
Al-Nahhas
Angel
A
Soriano
Gaia
G
Grassetto
Domenico
D
Rubello
Stefano
S
Fanti
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D018394:CA-125 Antigen / Q000097:blood*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D010051:Ovarian Neoplasms / Q000097:blood* / Q000000981:diagnostic imaging* / Q000628:therapy; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D011379:Prognosis; D012372:ROC Curve; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D055815:Young Adult
D018394:CA-125 Antigen; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
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