P-0273 Hepatic Metastasis and Reccurence of Colorectal Cancer Assesment by 18FDG PET/CT

Abstract

ABSTRACT Introduction Liver is the most frequent long distance metastasis site of digestive cancer. Early and accurate detection of hepatic metastasis as well as of tumoral recurrence is an important objective, especially in colorectal cancer, due to the improved 5 year surveillance rates after metastasectomy compared to nonsurgical therapy. Aim: to assess the use of 18FDG PET/CT (18 fluorodeoxyglucose positron emission tomography and computed tomography) in the detection of hepatic metastasis and recurrence of colorectal cancer. Methods Our study took place in the Emergency Clinical County Hospital (Oradea, Romania) in collaboration with PET POZITRON Diagnostic Center (Oradea, Romania). We studied 48 patients (38 men and 10 women, aged 48-74 years) who were previously treated by surgery for colorectal cancer. The FDG-PET/CT examination was made with the Siemens Biograph 16 unit (Germany) at 1 hour after the automatic infusion of FDG, at doses previously adjusted to individual parameters of each patient. Afterwards the recurrence and/or metastasis diagnosis was confirmed by colonoscopy, histology or other imaging techniques. At the same time, CEA (carcinoembryonic antigen) was measured. The statistical analysis was made with the help of SPSS application (Statistical Package for the Social Sciences). Results The time interval between the surgical intervention and PET/CT evaluation varied between 6 months to 8 years, with a mean value of 2.6 years. Out of the 48 studied patients recurrence and/or metastasis were diagnosed in 36 (75%) patients, including 8(16.7%) recurrences, 26 (54.2%) metastasis and 2 (4.1%) recurrence with metastasis. The diagnosis sensibility of identifying recurrent colorectal cancer and hepatic metastasis was 93% and its specificity was 84%. Treatment plans were changed in 8 (16.7%) patients after PET/CT evaluation. Localised metastasis were detected in the liver and lungs of 2 (4.2%) patients who were referred to surgery instead of chemotherapy. 4 patients (8.3%) had disseminated metastasis and were referred to chemotherapy. 2 (4.2%) patients with high levels of CEA and indication of iv chemotherapy in which conventional imaging showed no lesions, had at PET/CT evaluation, the following aspects: 1 patient had a recurrence and was resent to surgery and the other one, had lung and bone metastasis being thus referred to radio and chemotherapy. In our study group besides hepatic metastasis we also found metastasis in: lung (9/36, 25%), abdominal cavity and mesentery (8/36, 22%), retroperitoneal (7/36, 19%). Other secondary localizations included bone, lymph nodes, peritoneum and brain but the preferred metastasis foci were liver and lung. In some patients, beside conventional imaging examinations, PET/CT offered restaging of the disease. Conclusion 18FDG PET/CT examination can detect with high sensibility and specificity tumoral recurrences and/or hepatic metastasis. At the same time, in patients with surgically treated colorectal cancer it can identify lesions with abnormal metabolic levels, incipient occult metastasis and can orientate therapeutic measures.