Introduction: Colorectal cancer (CRC) is the third most common cancer worldwide with the incidence of about 1,8 million newly diagnosed cases in 2018. According to the World Cancer Report 2014, in Bosnia and Herzegovina 6700 people died of cancer in 2014, and CRC was the cause of mortality in 724 patients (10%). Prevention programs including screening, state-of-the-art diagnostic modalities and therapeutic approaches to CRC are being constantly improved. Aim: Our study was designed to address the diagnostic accuracy of 18F-FDG PET/CT in the follow-up of CRC in patients with normal or elevated CEA. Methods: We retrospectively analyzed 50 patients previously diagnosed with CRC who were initially surgically treated. All patients were suspicious of recurrence and were referred to as 18F-FDG PET/CT for restaging between February 2014 and February 2019. Possible recurrence was indicated by rising CEA, equivocal radiological findings or clinical findings. Results: Out of a total of 50 patients for whom the follow-up of at least six months was available, 27 had CRC confirmed with the gold standard, and all 27 patients had 18F-FDG PET/CT positive for recurrence, giving a sensitivity of 18F-FDG PET/CT in detecting the recurrence of CRC of 100.0% (0.0% of false-negative FN results). Out of 23 patients with no signs of CRC recurrence on the gold standard, 19 were also 18F-FDG PET/CT negative, giving a specificity of 18F-FDG PET/CT in detecting the recurrence of CRC of 82.6%, and 17.4% of false-positive FP results. Out of 31 patients who were 18F-FDG PET/CT positive, 27 had it confirmed pathophysiologically or clinically, giving positive predictive value (PPV) of 18F-FDG PET/CT in detecting CRC recurrence of 87.1%; negative predictive value (NPV) was 100.0%, meaning all 19 patients showing no signs of CRC recurrence when imaged with 18F-FDG PET/CT were gold standard negative as well. Conclusion: 18F-FDG PET/CT proves to be a valid diagnostic tool in detecting recurrence in patients with CRC.
Key words: Colorectal cancer, 18-FDG PET/CT.
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