Prognostic Value of Follow-up FDG PET/CT in Stomach Cancer

Abstract

Introduction: The Centers for Medicare and Medicaid Services recently revised coverage of 18F-FDG PET/CT scans to only 3 posttherapy follow-ups for a tumor type per patient. The purpose of this study was to evaluate the added value of a fourth or subsequent follow-up PET/CT scans in clinical assessment and impact on management planning in patients with stomach cancer. Methods: This was a retrospective study in which a total of 4513 patients with biopsy-proven stomach cancer, who underwent PET/CT between 2010 and 2014 were identified. Among these, 553 patients had taken four or more follow-up PET/CT scans, for a total of 800 fourth and subsequent follow-up scans. Median follow-up from the fourth follow-up PET/CT scan was 23 months, ranging between 4˜54 months. The added value of each follow-up PET/CT scan result was determined by correlation with clinical assessment and consequent changes in treatment. Results: Of the 800 fourth and subsequent follow-up scans, 8 (1%) were interpreted as positive and 792 (99%) were interpreted as negative for local tumor recurrence or metastasis. PET/CT identified recurrent tumors in 4/700 (0.57%) of scan performed without clinical suspicion and ruled out disease in 96/100 (96%) of scan performed with prior clinical suspicion. Treatment changes were made after 5/800 (0.63%) PET/CT scans; new treatment was initiated after 3/800 (0.38%) scans and treatment was changed after 2/800 (0.25%) scans. Conclusion: Fourth and subsequent follow-up PET/CT scans performed after completion of primary treatment showed limited value in clinical assessment and management. However, they were helpful in excluding disease when performed in the presence of clinical suspicion.