Background: Recurrent ovarian cancer is refractory and resistant to treatment in most patients, and no effective treatment for it has been established. Starting a treatment when tumors still consist of micro foci may contribute to improvement of prognosis. Therefore, the early diagnosis of relapse is important.
Methods: Among patients with epithelial ovarian cancer in whom initial treatment achieved remission between April 1998 and December 2003, those patients in whom the cancer-related antigen (CA)125 level was increased during the subsequent follow-up period, or those who showed abnormal computed tomography (CT)/magnetic resonance imaging (MRI) findings despite normal CA125 levels, were examined by 18F-fluoro-2-deoxyglucose - positron emission tomography (FDG-PET). We compared the rates of accurate diagnosis of recurrence achieved using CT/MRI, CA125, and FDG-PET in patients with a definitive diagnosis of relapse.
Results: We investigated 29 patients with epithelial ovarian cancer. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of FDG-PET were 84.6% (22/26), 100% (3/3), 100% (22/22), 42.9% (3/7), and 86.2% (25/29), respectively. These values were higher than the corresponding values obtained using CT/MRI or CA125 levels.
Conclusion: FDG-PET may be very useful for identifying sites of recurrent ovarian cancer, although this procedure had a low NPV because of the high rate of false-negative findings for micro or cystic lesions.