The diagnostic value of PET/CT for primary ovarian cancer--a prospective study

To prospectively evaluate the diagnostic value of combined PET/CT in detecting a malignant tumor in patients with no previous cancer history, presenting with a pelvic mass.

From September 2004 to March 2006, 101 patients (median age=60 years, range=24-85 years) with a Risk of Malignancy Index (RMI)>150 based on serum CA-125, ultrasound examinations (US) and menopausal state, were referred to PET/CT within 2 weeks prior to standard surgery/debulking of a pelvic tumor. Histological specimens from 97 patients were evaluated and the histological diagnoses were compared to the PET/CT results to calculate the diagnostic value of PET/CT in differentiating between malignant and borderline/benign tumors. Four patients refrained from surgery or biopsy.

The average serum CA-125 in the 97 studied patients was 784 U/ml (range=22-9665 U/ml). PET/CT demonstrated areas of abnormally increased metabolic activity considered highly suspicious for malignant tumor in 60 patients (62%). In 37 patients (38%) the tumors were considered benign on PET/CT. Histopathology showed benign tumors in 40 patients and malignant tumors in 57 patients. The sensitivity and specificity for PET/CT in diagnosing a malignant pelvic tumor were 100% (57/57) and 92.5% (37/40), respectively (P<0.00005).

Combined PET/CT demonstrates high diagnostic value in identifying primary ovarian cancer in patients with a pelvic mass of unknown origin and RMI>150. We suggest PET/CT as the image modality of choice when US shows a pelvic tumor and additional information prior to surgery is needed.