Assessment of biological and clinical aggressiveness of invasive ductal breast cancer using baseline 18F-FDG PET/CT-derived volumetric parameters

Abstract

The aim of this study was to evaluate the relationship of baseline fluorine-18-fluorodeoxyglucose PET/computed tomography (CT)-derived volumetric parameters for the primary tumor with clinicopathological risk factors and molecular subtypes in patients with invasive ductal breast carcinoma (IDBC). We evaluated 65 patients who underwent fluorine-18-fluorodeoxyglucose PET/CT for initial breast cancer staging. The association of maximum and mean standardized uptake values (SUVmax and SUVmean, respectively), metabolic tumor volume, and total lesion glycolysis (TLG) with clinicopathological risk factors and molecular subtypes was investigated and the discriminative power of significant features was assessed. All volumetric parameters were significantly higher for tumors measuring more than 2 cm and with a Ki-67 index of at least 20. Estrogen receptor (ER) and progesterone receptor (PR)-negative (ER-/PR-), human epidermal growth factor receptor 2-positive (HER2+), and triple-negative tumors showed increased SUVmax. SUVmax and SUVmean were higher for triple-negative and HER2+ IDBC than for ER+/HER2- IDBC. Metabolic tumor volume and TLG showed no differences among subtypes. All volumetric parameters correlated with the clinical tumor size and the Ki-67 index; these correlations differed among the different subtypes. Patients with systemic metastases showed significantly higher TLG. Receiver operating characteristic analysis showed that SUVmax had the highest discriminative power for the different subtypes, whereas TLG had a statistically significant discriminative power for systemic metastasis. SUVmax may appropriately reflect the immunohistochemical characteristics of IDBC, whereas TLG is associated with clinical risk factors and systemic metastasis. Our preliminary findings suggesting different relationships between volumetric parameters and the clinical tumor size and the Ki-67 index for different subtypes require further evaluation.