Correlation of tumor uptake on breast-specific gamma imaging and fluorodeoxyglucose PET/CT with molecular subtypes of breast cancer

Mechanisms of technetium-99m sesta-methoxyisobutylisonitrile (sestamibi) and (18)F-fluorodeoxyglucose (FDG) uptake by tumor are different. The purpose of this study was to investigate the association between the tumor uptake of these 2 tracers in invasive ductal carcinoma and to examine thecorrelation of uptake of each tracer with prognostic factors and tumor molecular subtypes. A total of 96 patients with invasive ductal carcinoma who underwent preoperative breast-specific gamma imaging and FDG positron-emission tomography/computed tomography were retrospectively enrolled. Tumor-to-background ratio (TBR) of sestamibi and maximum standardized uptake value (SUV(max)) of FDG were correlated with each other. Each of them was then compared with prognostic factors and molecular subtypes. In all tumors, there was a moderate positive correlation between TBR and SUV(max) (r = 0.520, P < .001). Both TBR and SUV(max) were significantly correlated with tumor size, incidence of axillary lymph node metastasis, histologic grade, estrogen receptor, progesterone receptor status, and Ki-67. There is a moderate degree of association between TBR of sestamibi and SUV(max) of FDG in the invasive breast cancer. Two imaging indexes showed the similar tendency related with prognostic factors and molecular subtypes. While both TBR and SUV(max) were significantly different between luminal A and nonluminal A tumors, neither of them had high enough sensitivity or specificity to obviate pathologic and molecular diagnosis.