Correlations of Primary Tumor SUVmax and Axillary Lymph Node SUVmax with Molecular Subtypes of Invasive Breast Cancer

Abstract

Breast cancer exhibits different molecular subtypes. Maximum standardized uptake value (SUVmax) has been reported as an independent prognostic factor in various cancers, including breast cancer. The ability of SUVmax to predict prognosis in breast cancer patients remains unclear. We aimed to investigate the relationships of the SUVmax of the primary tumor (PT) and axillary lymph nodes (ALN) with molecular subtypes of invasive breast cancer and axillary nodal burden. We analyzed data from 456 breast cancer patients whom ER, PR, HER2 (including FISH for IHC scores 2+), and Ki-67 statuses were available. Patients were classified into four molecular subtypes. PT SUVmax and ALN SUVmax were determined using preoperative 18F-fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG-PET/CT) scans. We evaluated the relationship between ALN SUVmax and axillary nodal burden in 229 patients, who were not treated with neoadjuvant therapy and for whom axillary surgery (sentinel lymph node biopsy and/or axillary lymph node dissection) data were available. Triple negative (TN) breast cancer exhibited the highest mean PT SUVmax (P<0.001); Luminal A (LA) tumors had significantly lower SUVmax than Luminal B (LB), HER2-positive (HER2+), and TN tumors (P=0.026, P=0.001, and P=0.001, respectively). Additionally, patients with HER2+ breast cancer exhibited higher ALN SUVmax than those with LA or LB breast cancer (P=0.001 and P=0.042, respectively). PT SUVmax and ALN SUVmax were significantly higher in patients with HER2+ breast cancer than in those with HER2-negative (HER2−) tumors (P=0.015 and P=0.002, respectively). Additionally, patients with high Ki-67 expression exhibited significantly higher PT SUVmax and ALN SUVmax than those with low Ki-67 expression (P<0.05). A strong correlation was found between ALN SUVmax and the number of ALN metastases (r = 0.812, p = 0.001). As a result of the dual comparisons, the ≥ 3 metastases group had a higher ALN SUVmax than the 1–2 metastases and no metastasis groups (p = 0.001 and p = 0.001, respectively). Our results confirmed the correlation between molecular subtype and PT SUVmax and ALN SUVmax. In addition, ALN SUVmax strongly correlated with axillary nodal burden. Therefore, 18F-FDG-PET/CT and SUVmax may provide useful information on molecular subtypes, tumor aggressiveness, and nodal burden in breast cancer and may help treatment decisions.