Evaluation of efficacy and clinical impact of FDG-PET in patients with suspicion of recurrent colorectal cancer

To evaluate the utility and clinical impact of Positron Emission Tomography with FDG (FDG-PET) in patients with suspected recurrent colorectal cancer (RCR). Eighty five (85) patients with suspicion of RCR (Group A: 35 for increased tumor markers and negative imaging tests, Group B: 25 operable malignant lesions and Group C: 25 with non-conclusive morphological tests) were studied retrospectively. In all patients a whole body scan was performed with FDG-PET. In 29 cases the results were confirmed by histology and clinical evolution (follow-up period > 12 months) and imaging test in 56. Prevalence of RCR was 89.4 %. FDG-PET was positive in 30/35 patients in Group A, with confirmation in 29 cases (PPV: 96.6 %) and 4/5 were true negative (TN) (NPV: 80 %). FDG-PET enabled surgery for 6 patients. In Group B, PET was positive in 22/25, and all of them had confirmation (PPV: 100 %) but surgery was performed in only 7 patients. NPV was 66.6 %. Out of the 25 cases of Group C, FDG-PET obtained 21 TP, 1 FP case, 1 TN, 2 FN, and was able to avoid surgery in 8 patients (PPV: 95.4 % and NPV: 33.3 %). Overall sensitivity, specificity, PPV, NPV and accuracy were 94.7 %, 77.7 %, 97.2 %, 63.3 % and 92.9 %, respectively. FDG-PET has high clinical impact in patients with suspicion of recurrent colorectal cancer, and should be incorporated in the diagnostic protocols before making a surgery decision.