Low baseline breast TLG and axillary MTV independently predict pathological complete response in HR-positive/HER2-negative breast cancer

This study aimed to investigate the role of metabolic parameters, including maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG), obtained from 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) scans before neoadjuvant chemotherapy (NACT) in predicting pathological complete response (pCR) in patients with locally advanced hormone receptor (HR)-positive/human epidermal growth factor receptor-2 (HER2)-negative breast cancer. A retrospective analysis was conducted on 137 patients diagnosed with axillary lymph node-positive, HR+/HER2- breast cancer who underwent NACT between February 2020 and January 2025. Metabolic parameters (SUVmax, MTV, TLG) of the primary breast tumor and axillary lymph nodes were recorded before treatment. Optimal threshold values were determined for parameters predicting pCR using ROC curve analysis, and independent predictors were identified using logistic regression analysis. pCR was observed in 19.0% (n=26) of the 137 patients in our study group. In univariate logistic regression analysis, grade 3 tumors (p=0.033), Ki-67 ≥20% (p=0.007), Breast SUVmax <14.25 (p=0.002), Breast MTV <15.55 (p=0.001), Breast TLG <73.32 (p=0.001), Axillary SUVmax <4.55 (p=0.006), Axillary MTV <14.32 (p<0.001), and Axillary TLG <45.45 (p<0.001) were significantly associated with achieving pCR. Multivariate logistic regression analysis of these variables identified Breast TLG <73.32 (p=0.022) and Axillary MTV <14.32 (p<0.001) as independent predictors of pCR after NACT. Pretreatment volumetric metabolic parameters obtained from 18F-FDG PET/CT may provide clinically useful predictive information in HR+/HER2-negative locally advanced breast cancer. Low Breast TLG and low Axillary MTV were independently associated with increased likelihood of achieving pCR after NACT.