Prediction of macrometastasis in axillary lymph nodes of patients with invasive breast cancer and the utility of the SUV lymph node/tumor ratio using FDG-PET/CT

Abstract

BackgroundAxillary lymph node dissection (ALND) is important for improving the prognosis of patients with node-positive breast cancer. However, ALND can be avoided in select micrometastatic cases, preventing complications such as lymphedema or paresthesia of the upper limb. To appropriately omit ALND from treatment, evaluation of the axillary tumor burden is critical. The present study evaluated a method for preoperative quantification of axillary lymph node metastasis using positron emission tomography/computed tomography (PET/CT).MethodsThe records of breast cancer patients who received radical surgery at the Gifu University Hospital (Gifu, Japan) between 2009 and 2014 were reviewed. The axillary lymph nodes were preoperatively evaluated by PET/CT. Lymph nodes were dissected by sentinel lymph node biopsy (SLNB) or ALND and were histologically diagnosed by experienced pathologists. The maximum standardized uptake value (SUVmax) was measured in both the axillary lymph node (SUV-LN) and primary tumor (SUV-T). The SUV-LN/T ratio (NT ratio) was calculated by dividing the SUV-LN by the SUV-T, and the efficacies of the NT ratio and SUV-LN were compared using receiver operating characteristic (ROC) curve analysis. The diagnostic performance was also compared between the techniques with the McNemar test.ResultsA total of 171 operable invasive breast cancer patients were enrolled, comprising 69 node-positive patients (macrometastasis (Mac): n = 55; micrometastasis (Mic): n = 14) and 102 node-negative patients (Neg). The NT ratio for node-positive patients was significantly higher than in node-negative patients (0.5 vs. 0.316, respectively, P = 0.041). The NT ratio for Mac patients (0.571) was significantly higher than in Mic (0.227) and Neg (0.316) patients (P <0.01 and P = 0.021, respectively). The areas under the curves (AUCs) by ROC analysis for the NT ratio and SUV-LN were 0.647 and 0.811, respectively (P <0.01). In patients with an SUV-T ≥2.5, the modified AUCs for the NT ratio and SUV-LV were 0.757 and 0.797 (not significant).ConclusionThe NT ratio and SUV-LN are significantly higher in patients with axillary macrometastasis than in those with micrometastasis or no metastasis. The NT ratio and SUV-LN can help quantify axillary lymph node metastasis and may assist in macrometastasis identification, particularly in patients with an SUV-T ≥2.5.Electronic supplementary materialThe online version of this article (doi:10.1186/s12957-014-0424-2) contains supplementary material, which is available to authorized users.

Initial Fludeoxyglucose (18F) Positron Emission Tomography-Computed Tomography (FDG-PET/CT) Imaging of Breast Cancer – Correlations with the Primary Tumour and Locoregional Metastases

“…The effect of tumour size and the extent of metastatic axillary LN involvement on prognosis were emphasized in many studies [22,33–36]. In our study, the mean tumour size of the LABC patients with metastatic LNs was significantly larger than that of the non-LABC patients who have a more favourable prognosis.…”

“…In a relatively large scale study, SUV max -T values in patients with negative LNs and metastatic LNs were 4.6±3.6 and 7.9±5.2, respectively [43]. In another large-scale study including 171 operable invasive BC patients, mean SUV max -T values in axillary LN-positive and LN-negative groups were 6.165 and 3.954, respectively [22]. SUV max -T was significantly higher in BC patients with progression compared to patients who were disease-free (10.6±5.1 vs. 4.7±3.5) [43].…”

“…Recently, “NT ratio” was introduced as a new PET/CT parameter and was found to be useful in evaluating metastatic LNs in non-small cell lung cancer [45] and BC [22]. In the above-mentioned study with BC patients, researchers found that the NT ratio differed significantly between LN positive (0.500) and LN negative cases (0.316).…”

“…In the above-mentioned study with BC patients, researchers found that the NT ratio differed significantly between LN positive (0.500) and LN negative cases (0.316). Moreover, they emphasized the usefulness of the NT ratio in quantifying axillary macrometastasis similarly to that of nodal SUV, especially in cases with tumoural SUV greater than 2.5 [22]. Similarly, in our study the mean NT ratio of the LABC group (0.918±0.605) was significantly higher than that of the non-LABC group (0.184±0.057), and we concluded that the NT ratio can be used as a promising quantitative parameter for the evaluation of axillary LNs suspected to be metastatic.…”

“…With regard to the metastatic axillary LNs, the ones with the highest SUV values within a particular region were selected. The NT ratio was calculated by dividing SUV max -LN by SUV max -T [22]. Mean NT ratios of axillary LNs were obtained and compared.…”