Lymphatic tumor burden negatively impacts the ability to detect the sentinel lymph node in breast cancer.

Sentinel lymph node (SLN) biopsy is the preferred method of nodal breast cancer staging. Techniques of SLN biopsy rely on transport of interstitial molecules through mammary lymphatics. Lymphatic flow may be disrupted by tumor emboli. Increased lymphatic tumor burden may be responsible for failure to identify the sentinel lymph node in patients with breast cancer. A prospective database of 110 patients who had SLN biopsy between January 2001 and December 2002 was analyzed. The number of metastatic axillary lymph nodes was used as a measure of lymphatic tumor burden. SLN was found in 94 per cent of cases. It was not found in seven patients; five of them had extensive axillary metastases (71%) compared to 23 per cent when SLN was found (P = 0.001). The average number of metastatic lymph nodes was larger when SLN was not found compared to when SLN was found (12.8 vs. 3.9, respectively, P = 0.002). Increasing numbers of metastatic nodes correlated with decreasing success in SLN biopsy (P = 0.075). The incidence of axillary metastases is higher in patients in whom the sentinel node is not found. High lymphatic tumor burden may have a causative role in SLN biopsy technical failure. Axillary dissection should be performed if SLN is not found, regardless of the tumor size or histology.