The role of subareolar methylene blue in identifying the sentinel node in patients with invasive breast cancer

Background

Recent studies have demonstrated that the sentinel node biopsy (SNB) is a reliable and minimally invasive method for determining the axillary node status in patients with breast cancer. However, the methods used for identifying the sentinel node (SN) are heterogenous with variable success rates. Some studies have reported low success rates with methylene blue (MB) dye for the identification of the SN. The present study aims to examine the accuracy of a simple method using subdermal injection of MB in the subareolar region.

Patients and method

A total of 35 women with operable invasive breast cancer undergoing axillary lymphadenectomy were recruited at our centre over a 4-month period (April-July 2000). The SN was identified in the axilla after injecting 1 ml of 1% MB in the subareolar region. The technical success rate, sensitivity and negative predictive value of this simple method were calculated. Furthermore, the cost-benefit of using MB rather than isosulfan blue as the labelling agent was determined.

Results

The SN was successfully identified in 34 (97%) out of 35 patients. Thirteen (37%) out of 35 patients had metastasis in the axillary nodes. The SN correctly predicted the presence of axillary disease in 12 (92.3%) out of 13 cases. The negative predictive value for SN was 96% (22/23). We have estimated that the use of MB rather than isosulfan blue as the labelling agent would save approximately £1.3 million/year in the UK, should the SNB become the standard of care.

Conclusion

Subareolar MB for identifying the SN in patients with operable invasive breast cancer provides a simple and reliable technique that can be used widely.