The clinical value of tumor FDG uptake for predicting axillary lymph node metastasis in breast cancer with clinically negative axillary lymph nodes

Objective: The aim of this study was to evaluate the clinical value of 18F-fluorodeoxyglucose (FDG) uptake and the clinicopathological or immunohistochemical findings of the primary tumor to predict axillary lymph node (ALN) metastasis in breast cancer with clinically negative ALN. Methods: This study retrospectively enrolled 104 women (49.43 ± 9.9 years) having breast cancer with clinically negative ALN using all types of preoperative imaging modalities including ultrasonography, FDG positron emission tomography, and magnetic resonance imaging. All cases of breast cancer in this study were proven as invasive ductal carcinoma with ≥1 cm in size. The final diagnosis of ALN status was confirmed by permanent pathology after operation. Results: Among 104 breast cancers with clinically negative ALN, 21 breast cancers (20.2 %) were proven to have ALN metastasis. The ROC curve analysis showed that the best cut-off value of SUV_max for identifying ALN metastasis was 9.8 with 33.3 % sensitivity and 92.8 % specificity (AUC = 0.656; p = 0.027). The multivariable analysis revealed that primary tumors with SUV_max >9.8 (p = 0.011) and D2-40 positivity (p = 0.027) were independently associated with ALN metastasis with odds ratios of 5.516 (CI 1.475-20.6333) and 3.409 (CI 1.154-10.072), respectively. Conclusion: Our study demonstrates that the incidence of ALN metastasis in even rigorously clinically evaluated breast cancer without suspiciously positive ALN is still not negligible, and while a high SUV_max of the primary tumor may be associated with a higher incidence of ALN metastasis in breast cancer with clinically negative ALN, a low SUV_max does not exclude ALN metastasis.