Clinical relevance of multiple sentinel nodes in patients with breast cancer

Background. Indiscriminate removal of axillary nodes may not be justified as it may potentially worsen the morbidity of the sentinel lymph node biopsy (SNB) procedure. This study examined the factors associated with removal of multiple sentinel lymph nodes and determined whether there was an upper threshold for the number of sentinel nodes that should be removed. Methods: A total of 803 patients with breast cancer underwent successful SNB using peritumoral injection of Tc-99m-labelled albumin colloid and Patent Blue V dye. SNB was followed by standard axillary treatment at the same operation in all patients. Results: The mean number of sentinel nodes removed per procedure was 2.2 (range 1-9). Multiple sentinel nodes (mean 2(.)9, range 2-9) were found in 501 patients (62(.)4 per cent). The false-negative rate in patients who had one sentinel node harvested was 10 per cent, compared with 1 per cent in patients who had three or more nodes removed (P = 0.010). Factors associated with finding multiple sentinel nodes were age less than 50 years (P = 0(.)004), low body mass index (P < 0.001), tumour in the outer half of the breast (P = 0(.)013), sentinel node visualization on lymphoscintigraphy (P < 0.001) and an interval of 12 h or less between radioisotope injection and SNB (P = 0(.)014). For 99(.)6 per cent of node-positive tumours, metastasis was detected within the first four sentinel nodes removed. Conclusion: The identification of multiple sentinel nodes, when present, reduced the false-negative rate. These data suggested that removal of more than four nodes was unnecessary.