How does 18f-FDG PET-CT scan affect clinical judgment and change treatment decisions in patients with epithelial ovarian cancer?

Abstract

5053 Background: The aim of the study was to determine the indications of PET-CT assessments in patients with epithelial ovarian cancer (EOC); to find out the concordance ratio of PET-CT results with the results of CT scans and CA-125 levels and finally to determine how PET-CT scan affects clinical judgment and changes treatment decisions. Methods: The files of 540 patients with EOC followed-up between January 2003 and December 2009 in our outpatient clinic were retrospectively analyzed. Among 540, 105 patients were evaluated with at least one PET-CT, with a total number of 116 scans. 80% of patients had serous papillary histology. 61% of patients had one PET-CT whereas 29% had two and 10% had three. 28.5% of PET-CT was done in the first-line treatment course, 39.5% was done in the second line and 16% was done in the third line. Results: The indications for PET-CT imaging were assigned as; isolated high levels of CA-125 (21%), determination of metastatic sites (58%) and presence of discordance between CA-125 levels and CT scan findings (21%). CT scan findings were in concordance with PET-CT in 23% of patients. CT scans determine extra lesions that were negative in PET-CT in only 4% of patients. In 50% of patients PET-CT was more effective to find out lesions that were negative in CT images. The ratio of lesions that were found to be positive in PET-CT but negative in CT scans were as follows; peritoneal implants (43%), intraabdominal lymphadenopathies (31%), intraabdominal solid lesions (21%), hepatic lesions ( 21%), extraabdominal lymphadenopathies (18%). PET-CT was found to change the treatment decisions in 51% of all patients. In the subgroup of patients with isolated CA-125 elevations, PET-CT changed the treatment decisions in 79%. In patients in whom PET-CT was performed before secondary cytoreductive surgery (n = 69), the results of PET-CT changed the treatment choices in 68% of patients. Conclusions: PET-CT is an important tool in the evaluation and management of patients with EOC. Especially in patients with isolated CA-125 elevation and patients planning to undergo secondary cytoreductive surgery, PET-CT is complimentary to CT scan and has an impact on clinical judgment and treatment decisions. No significant financial relationships to disclose.