Introduction. Early detection of recurrence is an important factor for long
term survival of patients with colorectal cancer. Measurement of serum levels
of carcinoembryonic antigen has been commonly used in the postoperative
surveillance of colorectal cancer. The purpose of this study was to evaluate
the ability of positron emission tomography-computed tomography to detect
pathological substrate of elevated serum carcinoembryonic antigen in patients
with colorectal cancer. Material and Methods. The patients with colorectal
cancer who underwent curative surgical resection and/ or chemotherapy, who
were found in our database, were analyzed retrospectively. Forty-eight 18F-
fluorodeoxyglucose positron emission tomography-computed tomography studies
including 45 patients (14 women, 31 men; mean age: 62.93 years) with elevated
serum, carcinoembryonic antigen levels, which had been performed between
January 2011 and January 2014, were evaluated. Serum levels of
carcinoembryonic antigen were measured within 3 months after positron
emission tomography-computed tomography examination. Final diagnosis of
recurrence was made by histopathological findings, radiology studies or
clinical follow-up. Results. Recurrences were diagnosed in 37 patients, the
prevalence being 77.1%. Liver metastases were found in 18 patients,
abdominal, pelvic and/or mediastinal lymph nodes were positive in 19
patients, 11 patients had loco regional recurrences and 4 patients had
pulmonary metastasis, and bone metastases were found in one patient. One
patient was diagnosed with metastasis in scar tissue. The overall sensitivity
and specificity of positron emission tomography-computed tomography was
90.24% and 71.42%, respectively. The positive and negative predictive values
were 94.87% and 55.56%, respectively. Conclusion. 18F- fluorodeoxyglucose
positron emission tomography-computed tomography is a powerful tool that
could be used in determining colorectal cancer recurrence in patients with
elevated carcinoembryonic antigen levels and could have an important clinical
impact on the management in patients with suspected recurrent colorectal
cancer.
Association between carcinoembryonic antigen levels and the applied value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in post-operative recurrent and metastatic colorectal cancer