Case of the Month—August 2005

FDG-PET for Metastatic Breast Cancer

History and Findings
A 50-year-old female presented with a history of breast cancer. Three years ago, a 2-cm nodule was detected in the lingual region of the lung. A PET scan was performed in November 2002 that showed multiple areas of increased FDG uptake in the left lung, left hilum, right chest wall, and liver (Figure 1).

The patient then received chemotherapy. A repeat PET study in August 2003 showed complete resolution of the abnormal uptake, indicating good response to the therapy (Figure 2).


Figure 1 November 2002	Figure 2 August 2003	Figure 3 August 2005

The patient was in remission until one month ago when a lab test revealed elevated CA125, CEA, and CA15-3. A chest CT and bone scan were performed and failed to detect significant abnormality. PET was performed (Figure 3) and showed multiple foci of increased FDG uptake in the left humerus, right SI joint, and bilateral femora that is consistent with bone metastases. The PET also detected recurrent cancer in the liver.

How Did PET Help?
In this case, PET helped to detect initial metastatic breast cancer and recurrence after therapy. PET also helped to evaluate the chemotherapy response after the initial therapy.

Discussion
18F-FDG PET has been found to be superior to bone scans in detecting bone metastasis in various malignant diseases, including breast cancer. FDG-PET often detects early marrow involvement before an identifiable bone reaction. Although 18F-FDG-PET has been reported as being appropriate for detecting all types of bone metastasis including lytic, sclerotic, and mixed lesions, it is more sensitive in detecting lytic metastasis than sclerotic metastasis. Quantitative assessment of therapy-induced changes in tumor F-FDG uptake may allow the prediction of both tumor response and patient outcome very early in the course of therapy. Treatment may be adjusted according to the chemosensitivity and radiosensitivity of the tumor tissue in an individual patient. Thus, 18F-FDG-PET has an enormous potential to reduce the side effects and costs of ineffective therapy.

Download the August 2005 Case of the Month (560 kb) as a PDF document.

Return to Case of the Month list.