Tumor Heterogeneity Assessed by 18F-FDG PET/CT Is Not Significantly Associated with Nodal Metastasis in Breast Cancer Patients.

INTRODUCTION The purpose of this study was to evaluate the association of tumor heterogeneity as assessed by positron emission tomography/computed tomography (PET/CT) with pathological factors of breast cancer, and the prediction of nodal metastasis through tumor heterogeneity. METHODS From January 2013 to December 2013, 102 patients with invasive ductal carcinoma of the breast were enrolled into this study. [18F]Fluorodeoxyglucose PET/CT was performed before surgery. The metabolic tumor volume (MTV) of each lesion was calculated and a series of standardized uptake value (SUV) thresholds (e.g. 40%, 50%, 60%, 70%, and 80% of SUVmax) was obtained. A threshold-volume (dV/dT) curve was acquired by plotting thresholds to MTV values automatically calculated with these thresholds. Tumor heterogeneity was calculated from the slope of the threshold-volume curve and defined as heterogeneity factor (HF). RESULTS HF differed significantly according to T stage (p < 0.0001), N stage (p = 0.0131) and American Joint Committee on Cancer (AJCC) stage (p = 0.0006). Among the pathological parameters, dermal lymphatic involvement (p = 0.0039) showed the significant correlations with HF. Lymphovascular invasion (p = 0.0005) was the only independent factor for predicting nodal metastasis. CONCLUSIONS Tumor heterogeneity measured by 18F-FDG PET/CT is significantly associated with dermal lymphatic involvement. However, PET might not be able to predict nodal metastasis in breast cancer.