Use of methylene blue dye for lymphatic basin mapping and sentinel lymph node biopsy in breast cancer patients in Enugu, Nigeria.

ABSTRACT

Background: Sentinel lymph node biopsy is the current standard of care for axillary staging and further treatment planning in patients with clinical axillary node-negative breast cancer. Sentinel node (SN) biopsy was designed to accurately stage the axilla and minimize the side effects of conventional axillary-lymph-node dissection without sacrificing oncologic outcomes. Sentinel lymph node biopsy is normally performed with nuclear scan and patent blue violet or isosulfan blue. These are expensive and not commonly available in resource-poor regions such as West Africa. Methylene blue dye is a commonly used agent in a wide range of clinical diagnostic procedures and has been used by other investigators to perform this procedure. This study was designed to demonstrate the feasibility and effectiveness of SN biopsy in the management of axillary node-negative breast cancer in resource-limited populations using methylene blue dye. Aim: To determine the efficacy of methylene blue dye as a single tracer in lymphatic basin mapping and sentinel lymph node biopsy in patients with clinical axillary node-negative breast cancer. Methods: This was a prospective, case-controlled study involving 28 consecutively presenting female patients with clinical axillary node-negative breast cancer at the University of Nigeria Teaching Hospital, Enugu. Each of the patients had lymphatic basin mapping and sentinel lymph node biopsy with a sub-areola-subdermal injection of methylene blue dye. The SN (s) were then removed using the dye as the marker. Each patient then had a mastectomy or wide local excision as appropriately planned and conventional levels I and II axillary dissection was performed in the same sitting. The SNs and other axillary nodes were reviewed independently by our institution's pathologist. Each patient's axillary dissection specimen acted as her control for the study. Results: The SNs were identified in 24 (85.7%) patients. There was a demonstrable learning curve with an improvement in identification rate in the later half of the cases (92.9%) compared to the earlier half of the cases (78.6%). A range of 1-3 nodes and a mean of 1.78 nodes were obtained. A sensitivity of 90.9%, specificity of 79.6%, false-positive rate of 28.6%, false-negative rate of 9.1%, and accuracy of 95.8% were obtained. There was no incidence of allergic/hypersensitivity reaction. Conclusion: Sentinel lymph node biopsy with methylene blue dye can be applied with high accuracy within resource-limited environments. However, there is a definite short learning curve that must be overcome and the procedure validated before clinical application in decision-making.