The value of primary tumor ¹⁸F-FDG uptake on preoperative PET/CT for predicting intratumoral lymphatic invasion and axillary nodal metastasis

Background: The preoperative evaluation of axillary lymph node (LN) status is important for prognostic prediction of breast cancer. We investigated the ability of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) to predict intratumoral lymphatic invasion and axillary LN metastasis. Methods: The preoperative ¹⁸F-FDG PET/CT images and pathologic reports for 428 breast cancer patients between January 2003 and December 2008 were evaluated retrospectively. The maximum standardized uptake value (SUV_max) of the primary tumor on ¹⁸F-FDG PET/CT, the degree of lymphatic invasion, and axillary LN metastasis identified by pathologic reports were assessed. Univariate and multivariate logistic regression analyses were performed to identify the significant features of the primary tumor that were associated with pathologically confirmed axillary LN metastasis. Results: The mean SUV_max of primary tumors with lymphatic invasion was higher than that of tumors without lymphatic invasion (5.13 ± 3.49 vs. 3.00 ± 2.47; p < 0.0001). The mean SUV_max of primary tumors with pathologically confirmed axillary LN metastasis was higher than that of tumors without LN metastasis (4.93 ± 3.32 vs. 3.22 ± 2.78; p < 0.0001). The degree of lymphatic invasion correlated strongly with axillary LN metastasis (p = 0.0001). Multiple logistic regression analysis showed that the high SUV_max of the primary tumor (>2.8), the high SUV_max of the axillary LN (>0.72) and the degree of lymphatic invasion were significant predictive factors of the development of axillary LN metastasis. Conclusion: Breast cancer patients with higher primary tumor ¹⁸F-FDG uptake are at higher risk of concurrent intratumoral lymphatic invasion and axillary LN metastasis.