Disease Restaging and Diagnosis of Recurrent and Metastatic Disease Following Primary Therapy with FDG-PET Imaging

Abstract

FDG PET and PET/CT are useful tools for restaging breast cancer patients who have undergone primary therapy, particularly in those with advanced stages, equivocal findings at conventional staging studies or asymptomatic with elevated tumor markers. In the clinical setting, they should be used to answer specific clinical questions and to complement conventional staging studies, not as a replacement. Evaluation of locoregional recurrences involving the skin, breast and chest wall with FDG PET and PET/CT can be problematic due to poor accuracy and diagnosis is usually made by histologic confirmation. For evaluation of distant metastases, FDG PET and PET/CT perform significantly better than conventional staging studies, particularly for the detection of nodal disease and osteolytic skeletal metastases, and therefore a more accurate method of determining the true extent of disease. One exception is the detection of sclerotic bone metastases; these lesions are not metabolically active enough for FDG PET detection but readily are detected by bone scan. PET/CT enhances diagnostic confidence (with marginal improvement in accuracy) compared to FDG PET alone for the evaluation of metastatic disease. FDG PET and PET/CT can also help in the assessing the treatment response of metastases earlier than conventional imaging. Serial FDG PET or PET/CT more accurately reflects disease status in patients with bone-dominant disease undergoing systemic treatment compared to conventional methods. Preliminary investigations show that FDG PET has the greatest impact on the choice of treatment in patients with suspected or proven locoregional recurrence who are being considered for aggressive curative treatment and in the evaluation of treatment response in patients with metastatic disease.