Association of Breast Cancer with Different Molecular Subtypes and Ki67 Proliferation with 18F-FDG PET/CT

Aim: The main molecular factors affecting the aggressiveness of breast cancer are estrogen receptor, progesterone receptor, and human epidermal growth factor-2. We wanted to study how molecular subtypes make a difference in tumor metabolism and staging in 18F-FDG PET/CT. Materials and Methods: Between 2023 and 2024, 110 patients with breast cancer who presented to our nuclear medicine clinic for staging were included in the study. Results: There was no statistically significant correlation between the molecular classification of the patients and the SUVmax levels of the primary breast tumor (p = 0.055). There was a significant correlation between breast molecular types and the presence of lymph node metastasis (p = 0.032). Triple-negative and Luminal B type patients had a higher risk of lymph node metastasis compared to other molecular subtypes. There was a significant correlation between Ki67 proliferation and molecular subtypes (p = 0.000). We also found a significant correlation between Ki67 index and breast tumor and lymph node SUVmax levels (p = 0.000, p = 0.03). There was a significant correlation between Ki67 proliferation and the presence of lymph node metastasis (p = 0.000). Discussion: In the present study, we demonstrated that different molecular subtypes show different metabolic characteristics. We also revealed that tumor Ki67 levels cause metabolic differences, and tumors with high Ki67 levels on 18F-FDG PET/CT have an increased likelihood of lymph node metastasis. We think that Ki67 levels should be taken into consideration when interpreting lymph node positivity in these patients.