METHODS
A total of 179 patients were included in the study, and their primary tumor histopathological features, molecular subtypes, axillary lymph node (ALN) involvement, distant metastasis, and OS were evaluated and compared 18F-FDG PET parameters. Among the PET parameters, maximum standardized uptake value (SUVmax), mean SUV, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of the tumor and ALNs were examined.

RESULTS
Based on molecular subtypes, the metabolic parameters of tumors were at their lowest in the Luminal A group and had the highest values within the triple-negative BC group. The triple-negative BC subtype was associated with a higher Ki67 proliferation index. Tumor SUVmax was higher in patients who were estrogen receptor negative, progesterone receptor (PR) negative, had nuclear grade III, and had distant metastasis (p=0.021, p=0.001, p<0.001, p=0.014, respectively). Patients with distant metastasis, ALN metastasis, and internal mammary lymph node involvement had higher tumor TLG and MTV (respectively, p<0.001, p<0.001, p<0.001). Higher ALN SUVmax values were observed in patients with distant metastasis and those who were PR negative (p=0.016). The ALN TLG value was found to be higher in patients with distant metastases and ALN metastases compared to those without (p<0.001, p=0.049, p=0.025, respectively).

CONCLUSION
The study indicates that PET/CT is a highly dependable method for detecting ALN involvement. Furthermore, assessing metabolic tumor characteristics using 18F-FDG PET/CT before initiating primary IDC treatment might provide crucial diagnostic and prognostic insights that significantly contribute to managing the disease. Keywords : 18F-fluorodeoxyglucose positron emission; invasive ductal breast cancer; metabolic tumor volume; overall survival; tomography/computed tomography; total lesion glycolysis