Correlation between Histopathological Prognostic Tumor Characteristics and [F]FDG Uptake in Corresponding Metastases in Newly Diagnosed Metastatic Breast Cancer.

BACKGROUND

In metastatic breast cancer (MBC), [F]fluorodeoxyglucose positron emission tomography/computed tomography ([F]FDG-PET/CT) can be used for staging. We evaluated the correlation between BC histopathological characteristics and [F]FDG uptake in corresponding metastases.

PATIENTS AND METHODS

Patients with non-rapidly progressive MBC of all subtypes prospectively underwent a baseline histological metastasis biopsy and [F]FDG-PET. Biopsies were assessed for estrogen, progesterone, and human epidermal growth factor receptor 2 (ER, PR, HER2); Ki-67; and histological subtype. [F]FDG uptake was expressed as maximum standardized uptake value (SUV) and results were expressed as geometric means.

RESULTS

Of 200 patients, 188 had evaluable metastasis biopsies, and 182 of these contained tumor. HER2 positivity and Ki-67 ≥ 20% were correlated with higher [F]FDG uptake (estimated geometric mean SUV 10.0 and 8.8, respectively; = 0.0064 and = 0.014). [F]FDG uptake was lowest in ER-positive/HER2-negative BC and highest in HER2-positive BC (geometric mean SUV 6.8 and 10.0, respectively; = 0.0058). Although [F]FDG uptake was lower in invasive lobular carcinoma ( = 31) than invasive carcinoma NST ( = 146) (estimated geometric mean SUV 5.8 versus 7.8; = 0.014), the metastasis detection rate was similar.

CONCLUSIONS

[F]FDG-PET is a powerful tool to detect metastases, including invasive lobular carcinoma. Although BC histopathological characteristics are related to [F]FDG uptake, [F]FDG-PET and biopsy remain complementary in MBC staging (NCT01957332).