Study: Increased FDG uptake does not signify gastrointestinal cancer development

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In the case of an unremarkable CT, elevated esophagogastric or anorectal FDG uptake does not predict cancer development and does not have to be investigated further, according to a study in this month’s European Radiology.

Senior author Gerald Antoch, MD, from the department of diagnostic and interventional radiology and neuroradiology at University Hospital Essen, Germany, and colleagues noted that focal gastrointestinal F-18 FDG uptake can frequently be found on FDG PET/CT, even in patients without known gastrointestinal malignancy. Therefore, the researchers sought to evaluate whether increased gastrointestinal FDG uptake without CT correlate is an early indicator of patients developing gastrointestinal malignancies.

The investigators enrolled 1,006 patients without esophagogastric or anorectal malignancies underwent FDG PET/CT. The esophagogastric junction, the stomach and the anorectum were evaluated for increased FDG uptake. They assigned patients without elevated uptake to Group A, and patients with elevated uptake were allocated to Group B. They tested the SUVmax values of both groups for significant differences using the U test.

According to the authors, a follow up of longer than one year (mean 853 days) served as the gold standard. They also noted that 460 patients had to be excluded based on insufficient follow-up data.

For the remaining 546 patients, the mean SUVmax was as follows: (a) esophagogastric junction, Group A: 3.1 and Group B: 4; (b) stomach, Group A: 2.8, Group B: 4.1; (c) rectal ampulla, Group A: 2.8, Group B 3.9; (d) anal canal, Group A: 2.7, Group B: 3.9.

Finally, Antoch and colleagues reported that only one patient developed gastric cancer, and therefore, gastrointestinal F-18 FDG accumulation on PET without a corresponding CT abnormality is not an early indicator of cancer development.