Visceral fat metabolic activity evaluated by preoperative ¹⁸F-FDG PET/CT is independently associated with axillary lymph node metastasis in postmenopausal luminal breast cancer

Objectives: Obesity is known to increase breast cancer risk and aggressiveness in postmenopausal luminal breast cancer and obesity-driven dysfunctional metabolic activity in visceral adipose tissue (VAT) is considered as one of the principal underlying mechanism. We aimed to investigate the relationship between VAT metabolic activity evaluated by preoperative ¹⁸F-FDG PET/CT and axillary lymph node (ALN) metastasis in postmenopausal luminal breast cancer patients.

Methods: A total of 173 patients (131 with luminal type and 42 with non-luminal type) with newly diagnosed postmenopausal breast cancer were enrolled in this study. They all underwent preoperative ¹⁸F-FDG PET/CT and surgery. VAT metabolic activity was defined as the maximum standardized uptake value (SUVmax) of VAT divided by the SUVmax of SAT (V/S ratio).

Results: In luminal breast cancer, the patients with ALN metastasis showed significantly higher V/S ratio than the patients without ALN metastasis, whereas non-luminal breast cancer patients showed no difference of V/S ratio between positive and negative ALN metastasis groups. Furthermore, V/S ratio was significantly associated with ALN metastasis in luminal breast cancer patients by uni-and multivariate analyses. We also found that the erythrocyte sedimentation rate, which could reflect the systemic inflammatory condition, was significantly higher in ALN metastasis group than the negative ALN metastasis group in luminal breast cancer patients and showed significant positive correlation with V/S ratio.

Conclusions: V/S ratio significantly affects the ALN metastasis status in postmenopausal luminal breast cancer patients and it may be useful as a potential biomarker of obesity-driven systemic inflammation associated with tumor aggressiveness.