(18)F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Features in Locally Advanced Breast Cancer and Their Correlation with Molecular Subtypes

PURPOSE: (18)F-Fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) is now recognized as a staging investigation for locally advanced breast cancer. This retrospective review of data was performed to correlate the maximum standardized uptake value (SUV(max)) of the primary tumor with the molecular subtype of breast cancer. MATERIALS AND METHODS: Patients with biopsy-proven, treatment naïve, Stage III breast cancer, for whom (18)F-FDG PET/CT data and immunohistochemistry 4 was available were included in the study. Correlations were deduced between the SUV(max) of primary tumor to the molecular subtypes. RESULTS: Three hundred and two patients were included in the study. Fifty-two (17.2%) tumors were Luminal A (LA), 131 (43.4%) Luminal B (LB), 42 (13.9%) human epidermal growth factor receptor-2 enriched (HE), and 77 (25.5%) basal-like (BL). SUV(max) of the primary tumor differed significantly between LA and other subtypes (SUV(max): LA Median 7.4, LB 11.65, HE 13.5, BL 15.35, P < 0.001). Estrogen receptor (ER) and progesterone receptor (PR) positivity were inversely correlated to the SUV(max) of the primary (SUV(max): ER + Median 10.4, ER - 14.2, P < 0.001, PR + 9.65, PR − 13.9, P < 0.001). There was a strong positive correlation observed between Ki67 and SUV(max) (Pearson Coefficient 0.408, P < 0.001). A SUV(max) value of 9.65 was determined as a cutoff on receiver operating characteristic curve to differentiate between LA and other subtypes with a sensitivity of 92.3% and specificity of 70.6%. CONCLUSIONS: SUV(max) of primary showed a statistically significant difference between LA subtypes when compared to other subtypes. However, there was overlap of values in each subgroup and thus (18)F-FDG PET/CT cannot be used to accurately assess the molecular characteristics of the tumor.