Axillary Lymph Node-to-Primary Tumor Standard Uptake Value Ratio on Preoperative 18F-FDG PET/CT: A Prognostic Factor for Invasive Ductal Breast Cancer

PURPOSE This study assessed the axillary lymph node (ALN)-to-primary tumor maximum standard uptake value (SUVmax) ratio (ALN/T SUV ratio) in invasive ductal breast cancer (IDC) on preoperative (18)F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) to determine the effectiveness in predicting recurrence-free survival (RFS). METHODS One hundred nineteen IDC patients (mean age, 50.5±10.5 years) with pathologically proven ALN involvement without distant metastasis and preoperative FDG PET/CT were enrolled in the study. SUVmax values of the ALN and primary tumor were obtained on FDG PET/CT, and ALN/T SUV ratio was calculated. Several factors were evaluated for their effectiveness in predicting RFS. These included several parameters on FDG PET/CT as well as several clinicopathological parameters: pathologic tumor/node stage; nuclear and histological grade; hormonal state; status with respect to human epidermal growth factor receptor 2, mindbomb E3 ubiquitin protein ligase 1 (MIB-1), and p53; primary tumor size; and ALN size. RESULTS Among 119 patients with breast cancer, 17 patients (14.3%) experienced relapse during follow-up (mean follow-up, 28.4 months). The ALN/T SUV ratio of the group with disease recurrence was higher than that of the group without recurrence (0.97±1.60 and 0.45±0.40, respectively, p=0.005). Univariate analysis showed that the primary tumor SUVmax, ALN SUVmax, ALN/T SUV ratio, ALN status, nuclear and histological grade, estrogen receptor (ER) status, and MIB-1 status were predictors for RFS. Among these variables, ALN/T SUV ratio with hazard ratio of 4.20 (95% confidence interval [CI], 1.74-10.13) and ER status with hazard ratio of 4.33 (95% CI, 1.06-17.71) were predictors for RFS according to multivariate analysis (p=0.002 and p=0.042, respectively). CONCLUSION Our study demonstrated that ALN/T SUV ratio together with ER status was an independent factor for predicting relapse in IDC with metastatic ALN. ALN/T SUV ratio on preoperative FDG PET/CT may be a useful marker for selecting IDC patients that need adjunct treatment to prevent recurrence.