Breast Cancer Case Study
Clinical History
A 39 year old woman with history of breast carcinoma treated with left mastectomy and tamoxifen therapy in 2003 presented with enlarged neck nodes suspicious for metastases. The patient was referred for FDG PET•CT which was performed in September 2006.
Imaging Findings PET•CT Scan 9/12/2006 (Pre-treatment):
The FDG PET•CT study showed extensive FDG avid supraclavicular and mediastinal lymph node metastases involving bilateral hilar nodes as well as anterior mediastinal and prevascular nodes. Metabolically active celiac node metastases were also visualized (Fig. 4). There were multiple metastatic lung nodules in both lobes (Figs 1,2,3,4).
Based on the PET•CT findings the patient was classified as stage IV breast cancer and was put on Herceptin® chemotherapy and tamoxifen was continued. The patient was referred for a follow-up FDG PET•CT scan to evaluate therapeutic response in January 2007.
Imaging Findings PET•CT Scan 1/3/2007 (post chemotherapy):
The follow-up FDG PET•CT study performed in January 2007 showed complete resolution of previously metabolically active supraclavicular and mediastinal lymphadenopathy. The metabolically active lung parenchymal nodules also show partial resolution of activity suggesting therapeutic response (Fig. 5).
Imaging Findings Diagnostic CT Scan of Chest, Abdomen and Pelvis on 1/3/2007
The contrast CT study of the thorax and abdomen showed diffuse patchy opacities with nodularity in both lungs. In view of the significant decrease in metabolic activity of the mediastinal nodes and lung parenchymal metastases, the diffuse opacities shown in CT were deemed to be related to chronic indolent infection like Mycobacterium avium-intracellulare (MAI) which may occur in immunocompromised patients following chemotherapy.
Diagnosis
PET•CT Scan 9/12/2006
Based on the PET•CT findings the patient was classified as stage IV breast cancer and was prescribed Herceptin chemotherapy and the tamoxifen treatment was continued. PET correctly upstaged the patient and the appropriate chemotherapy was initiated.
PET•CT Scan 1/3/2007 (post chemotherapy)
The PET•CT scan showed successful response to Herceptin chemotherapy that was completed in December 2006.
Discussion
This study shows the value of PET in correctly staging the patient and guiding appropriate therapy as well as acting as an indicator of therapeutic response. Low FDG uptake in diffuse lung opacities seen in the CT scan was the guiding factor in differentiating metastatic disease from a chronic infection like MAI.
Herceptin (trastuzumab) is a monoclonal antibody targeting HER2 protein over-expressing metastatic breast cancer. As a targeted therapy, trastuzumab can show dramatic improvement in a selected group of patients as is evident from this case. Molecular imaging can act as a very effective tool for evaluation of therapeutic response as well as treatment modifications in cases where the response is inadequate.
Data courtesy of Dr. Charles Intenzo and Dr. Sung Kim, Jefferson Center City Imaging, Philadelphia, PA
References:
1. Initial experience with FDG-PET/CT in the evaluation of breast cancer – Tatsumi et al – Eur J of Nucl Med Mol Imaging 2006;33(3):254-62
2. Performance of 2-Deoxy-2-[F-18] Fluoro-D-glucose Positron Emission Tomography and integrated PET/CT in restaged breast cancer patients – Fueger et al – Mol Imaging Biol 2005;7(5):369-376
* Any of the protocols presented herein are for informational purposes and are not meant to substitute for clinician judgment in how best to use any medical devices. It is the clinician that makes all diagnostic determinations based upon education, learning and experience.