How many sentinel lymph nodes should we excise?

Objective

Radioactivity may be detected over several nodes during sentinel node biopsy (SNB), thus indicating that they all should be excised for examination. Biopsy of an insufficient number of lymph nodes (LNs) may produce a false negative result, while excision of too many contradicts the SNB idea itself, turning it into an incomplete lymphadenectomy. We aim at establishing the minimal number of LNs that must be removed without compromising the reliability.

Materials and methods

During years 2004 to 2008, 1,478 SNBs were performed in our department. Invasive cancer was diagnosed in 1,202 cases and these were included in our present study. LNs were removed one by one, according to the expressed radioactivity, until the last node showed radioactivity below 10% of the previous one. All LNs were marked in order of their expressed radioactivity and subsequent removal.

Results

Metastases were found in 228/1,202 (19%) patients with invasive breast cancer. The postoperative full pathologic report showed that 143/228 patients (62.7%) had no LN metastases other than to sentinel LNs; they were, however, found in the remaining 37.3%. The number of excised sentinel nodes varied from one to nine, the average was 2.04. Table 1 presents groups of patients with particular numbers of sentinel LNs excised and percentages of metastases found. In our experience, almost full (97%) information about the presence of metastases could be based on the biopsy of three first sentinel nodes, and in full (100%) of five first sentinel nodes.

Table 1

Conclusion

In most cases, full information about the presence of metastases to sentinel nodes could be obtained from the biopsy of the first three LNs, and 100% information of the first five. Biopsy of more than five LNs proved to be of no additional value.