Metastatic breast cancer is considered an unrecoverable disease, about 12% of patients diagnosed with breast cancer develop metastatic disease. Metastatic breast cancer is associated with a poor prognosis: 26% is the 5-year survival rate. Positron Emission Tomography - Computed Tomography (PET CT) is now more frequently used in breast cancer staging and follow-up. There is a strong relation between hormonal receptors in the tumor tissue and the response to hormone therapy and chemotherapy. Our prospective study includes 40 female patients with metastatic breast cancer who were treated in the Department of Clinical Oncology & Nuclear Medicine at Mansoura University Main Hospitals and Health Insurance Institute. This study aims to see how different molecular subtypes affect fluorodeoxyglucose (FDG) avidity in different metastatic lesions in patients with metastatic breast cancer who are undergoing PET/CT, as well as to detect therapy response using PET-CT in metastatic breast cancer concerning different molecular subtypes.
The standardized uptake value (SUV) post-treatment value was statistically significantly lower in luminal A molecular subtype for bone metastases, and in luminal B+ molecular subtype for lung metastases, and a statistically significantly higher SUV post-treatment value in luminal B- molecular subtype for bone metastases. There is no other statistically significant difference in other luminal subtypes in different metastatic sites.
There was a statistically significant difference in treatment response (progressive vs. non-progressive) between the four molecular subtypes as in luminal A, and luminal B+ subtypes, none of the patients' progressive disease (PD). In luminal B-, 70% had PD (54% of PD had luminal B- subtype). In basal-like, 75% had PD (46% of PD had basal-like subtype).
FDA avidity in various metastatic lesions in patients with breast cancer undergoing PET/CT is affected by molecular subtyping (Luminal A, Luminal B+, Luminal B-, Basal-like). The poorest prognosis is associated with the basal-like subtype, whereas the most excellent prognosis is associated with the Luminal A subtype.
Keywords: Molecular subtypes, 18 FDG PET/CT, Metastatic breast cancer.
(Citation: Gastric & Breast Cancer 2022; 17(1): 12-26)