Lymphoscintigraphy in breast cancer patients after neoadjuvant chemotherapy

Summary The aim of this study was to evaluate the diagnostic value of lymphatic mapping by lymphoscintigraphy in breast cancer patients undergoing neoadjuvant chemotherapy (NCTX). We assessed the association between clinicopathological factors and nonvisualized sentinel nodes during preoperative lymphoscintigraphy. As secondary aims, we analyzed whether post NCTX axillary ultrasonography and fluorine-18 fluorodeoxyglucose positron emission tomography and computed tomography (F18-FDG-PET/CT) might be useful for staging in case of nonvisualized sentinel nodes. Patients, methods: 61 patients with newly diagnosed, invasive breast cancer potentially eligible for NCTX were included in this substudy of a prospective trial on the monitoring of NCTX with 18F-FDG PET/CT. In all patients, lymphoscintigraphy was performed prior to sentinel lymph node biopsy (SLNB). 42 patients received neoadjuvant chemotherapy. 19 patients did not receive NCTX. After SLNB, mastectomy or lumpectomy (breast-conserving surgery) combined with level I and II axillary lymph node dissection were performed. Cases of nonvisualized sentinel nodes were analyzed with respect to tumour and patient characteristics and the results of ultrasonography and 18F-FDG-PET/CT before and after NCTX. Results: Lymphoscintigram successfully identified at least one sN in 55 patients (i.e. identification rate of 90%). The risk of failure to identify the sN was associated statistically with a positive clinical nodal status prior to NCTX (p = 0.021). There was no statistical difference between patients with visualized and nonvisualized sN with respect to age, tumour grade, tumour size, pathological lymph node status or tumour histology. In patients without NCTX the sN identification rate was 100% versus 86% in patients with NCTX (n.s.). The FNR of patients with NCTX was 9.1%. Post NCTX axillary ultrasonography or FDG-PET/CT did not provide accurate information about the lymph node status in case of failing lymphatic mapping. Conclusion: On the basis of our findings, SLNB can not yet be recommended as a reliable staging method in breast cancer patients undergoing neoadjuvant chemotherapy. Patients with clinically positive axillary lymph nodes have a higher chance of unsuccessful lymphatic mapping by lymphoscintigraphy. Performing SLNB before NCTX in clinically node-negative patients may identify the subset of patients in whom axillary lymph node dissection can be omitted. Post NCTX axillary ultrasonography and 18F-FDG-PET/CT can not be suggested as valid axillary staging methods in case of a failed lymphatic mapping.