Diagnostic Performance of 18F-FDG PET/CT in Detecting Distant Metastases in Breast Cancer

Breast cancer is the most common cancer type and the most common cause of death in women worldwide.

Breast cancer patients with large tumours (T3) have a 8.3%-15.1% risk for distant metastasis. Metastatic breast cancer (MBC) is considered an incurable disease with a 5-year overall survival of only 25%.

Effective management of breast cancer requires accurate diagnosis and determination of the extent of the disease to select the most effective treatment approach. Breast cancer is very heterogenous and is characterized by different pathological features, with distinct responses to treatment and differences in long-term patient survival.

Various imaging modalities have been suggested for diagnosing MBC; however, contrast-enhanced computed tomography (CE-CT) and bone scintigraphy are often used in clinical practice. However, CE-CT has low sensitivity for bone metastases and low specificity for liver metastases.

CE-CT and the corresponding response evaluation criteria in solid tumours (RECIST) are methods that assess changes in structural lesions, making it challenging to differentiate between active tumour tissue and scar lesions [18F]-fluorodeoxyglucose-positron emission tomography/computed tomography ([18F] FDG-PET/CT) is a glucose analog transported via glucose transporters into the cells and phosphorylated by hexokinase .FDG follows the same pathway as glucose during the first enzymatic reactions in the cells, but because FDG lacks a hydroxyl group at the C-2 position, it is not metabolized further and is physically trapped in tumor cells at a rate proportional to glucose utilization.

Malignant cells show higher glucose metabolism and increased glycolytic activity compared to non-malignant cells (10). This high glycolytic activity eases the detection of malignant cells using [18F] FDG-PET/CT) imaging. so, [18F] FDG-PET/CT can detect changes in metabolic activity before morphologic changes can be seen.

However, the exact clinical stage at which PET/CT can be performed with well-balanced cost-effectiveness is uncertain till now .

• Inclusion criteria:

• Patients with pathologically proven breast cancer
• Metastatic breast cancer proved by pathology or radiological modalities.
• Interval between 18F-FDG PET/CT and CE-CT from one to three weeks.
• Exclusion criteria:

• Patients with known concomitant malignancy
• Patients receive systemic treatment chemotherapy or radiotherapy between 18F-FDG PET/CT and CE-CT.