Clinical impact of FDG-PET in the follow-up or suspicion of recurrent gastric cancer

Abstract

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Objectives: To evaluate the clinical contribution of positron emission tomography (PET) using ¹⁸F-fluorodeoxyglucose (FDG) in patients with follow-up or suspected recurrent gastric cancer.

Methods: We performed a retrospective review of 85 patients (M:F=56:29) who underwent 111 PET scans from March, 2002 to June, 2007 for post-treatment surveillance of gastric cancer. Of these patients, 43 patients were suspected of having recurrence by other imaging modalities or rising tumor markers (group A), and the remaining 42 patients underwent a PET scan without evidence of recurrence (group B). We only examined results for the first PET study after end of treatment. Diagnostic performance and prevalence of clinical impact of FDG-PET were analyzed. The gold standard was histopathology and/or clinical follow-up for at least 6 months.

Results: 31 patients (72%) had recurrence in group A and 8 patients (19%) in group B. In patient-basis, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy of FDG-PET were 61%, 67%, 83%, 40%, and 63%, respectively, in group A, and 50%, 94%, 67%, 89%, and 86%, respectively, in group B. There were 13 patients (30%) in group A, for whom PET findings contributed to determining patients’ therapeutic management, while there were only 4 patients (10%) in group B. Overall, the sensitivity, specificity, PPV, NPV, and diagnostic accuracy were 59%, 87%, 79%, 71%, and 74%, respectively. There were 4 cases (5%), in which positive PET findings depicted not recurrent foci, but spontaneous malignancies, such as lung cancer.

Conclusions: FDG-PET was considered helpful in patients with suspected recurrent gastric cancer, although contribution of PET results may be limited in patients without evidence of recurrence at the time of PET.