Is SUVmax of 18F-FDG PET/CT Predictive Factor for Malignancy in Gastrointestinal Tract?

BACKGROUND: Increasing use of 18F-FDG PET/CT in cancer patients, has led to more common detection of 18F- FDG uptake in the gastrointestinal tract (GIT). AIMS: The objective of this study was to assess 18F-FDG uptake in incidental and known GIT malignancy. METHODS: A total of 6500 patients followed-up in a single and tertiary center between January 2010 and September 2016 were retrospectively reviewed. Of 2850 patients assessed with 18FDG-PET/CT, known GIT malignancy and 18F-FDG uptake cases during follow-up were included in the study. RESULTS: Of 658 patients with 18F-FDG uptake, 150 patients who underwent endoscopy were included in the study. Seventy-seven of these patients had known GIT malignancy and 73 had incidental 18F-FDG uptake. Among these 73 patients; 7 (9.6%) had malignancy, 20 (27,2%) adenoma and 24 (32.9%) inflammation that were confirmed. Endoscopy was normal in 22 (30.2%) patients. One hundred forty-three (95.3%) patients had focal and 7 (4.7%) had diffuse uptake. While no malignancy was detected in patients with diffuse uptake, 58.7% (84/143) of the patients with focal uptake presented malignancy. Mean the standardized uptake value (SUV) max values were found as 15.0 ± 10.6 (range, 3.8-56.5) in malignant disease, 10.2 ± 4.3 (range, 2.4-19.7) in adenoma, 7.3 ± 3.6 (range, 3.6-18.7) in inflammation, and 9.8 ± 4.2 (range, 3.8-19.9) in normal endoscopy groups (p < 0.001, rho = 0.378). CONCLUSION: Although this study demonstrated high probability of malignant disease with increased 18F-FDG uptake in the GIT, it would be a more appropriate approach to confirm all patients with 18F-FDG uptake through endoscopy as SUVmax values vary in a wide range.

Comparison of survival with somatostatin analog and chemotherapy and prognostic factors for treatment in 165 advanced neuroendocrine tumor patients with Ki-67 20% or less.

The objectives of this study were to compare progression-free survival (PFS) with somatostatin analog (SSA) versus chemotherapy (CTx) in first-line therapy and to determine the patient group in which these treatments were more effective in neuroendocrine tumors (NETs) with a Ki-67 index of 20% or less. Patients who received SSA or CTx and had unresectable locally advanced and metastatic NETs with a Ki-67 index of 20% or less were retrospectively selected from 13 centers in the Turkish database between 2000 and 2015. One hundred and sixty-five patients were enrolled. The median age was 56 years and the male-to-female ratio was 1.09. Seventy-four (45%) patients were of grade 1 NET and 91 (55%) were of grade 2. SSA was given to 104 patients, whereas 61 were treated with CTx. The objective response rate after SSA was 15.4%; another 73.1% had stable disease. The objective response rate after CTx was 36.1%, and 40.9% had stable disease (P=0.008). The median PFS in SSA patients was 21 months (95% confidence interval: 12.4-29.6), and 8 months for CTx (95% confidence interval: 5.5-10.6) (P<0.001). There was no significant difference between PFS of receiving SSA and CTx in pancreatic neuroendocrine tumor (PNET) patients; however, the PFS of receiving SSA was longer in non-PNET patients (P<0.001). SSA was better treatment in advanced NET patients with a Ki-67 index of less than 5%, having a primary resected and a performance status of 0 (P<0.05). SSA may be preferred over CTx in advanced NET patients with low-to-intermediate grade.