Background: In women with breast cancer, sentinel-lymph-node biopsy (SLNB) provides information that allows surgeons to avoid axillary-lymph-node dissection (ALND) if the SLN does not have metastasis, and has a favourable effect on quality of life. Results of our previous trial showed that SLNB accurately screens the ALN for metastasis in breast cancers of diameter 2 mm or less. We aimed to update this trial with results from longer follow-up.
Methods: Women with breast tumours of diameter 2 cm or less were randomly assigned after breast-conserving surgery either to SLNB and total ALND (ALND group), or to SLNB followed by ALND only if the SLN was involved (SLN group). Analysis was restricted to patients whose tumour characteristics met eligibility criteria after treatment. The main endpoints were the number of axillary metastases in women in the SLN group with negative SLNs, staging power of SLNB, and disease-free and overall survival.
Findings: Of the 257 patients in the ALND group, 83 (32%) had a positive SLN and 174 (68%) had a negative SLN; eight of those with negative SLNs were found to have false-negative SLNs. Of the 259 patients in the SLN group, 92 (36%) had a positive SLN, and 167 (65%) had a negative SLN. One case of overt clinical axillary metastasis was seen in the follow-up of the 167 women in the SLN group who did not receive ALND (ie, one false-negative). After a median follow-up of 79 months (range 15-97), 34 events associated with breast cancer occurred: 18 in the ALND group, and 16 in the SLN group (log-rank p=0.6). The overall 5-year survival of all patients was 96.4% (95% CI 94.1-98.7) in the ALND group and 98.4% (96.9-100) in the SLN group (log-rank p=0.1).
Interpretation: SLNB can allow total ALND to be avoided in patients with negative SLNs, while reducing postoperative morbidity and the costs of hospital stay. The finding that only one overt axillary metastasis occurred during follow-up of patients who did not receive ALND (whereas eight cases were expected) could be explained by various hypotheses, including those from cancer-stem-cell research.