Sentinel lymph node mapping of breast cancer: a case-control study of methylene blue tracer compared to isosulfan blue.

Isosulfan blue has been traditionally used as a tracer to map the lymphatic system during identification of the sentinel lymph node. However, allergic reactions may be life threatening. We compared the efficacy of methylene blue dye as a tracer for sentinel lymph node biopsy to isosulfan blue dye. In an analysis of 164 cases, there was no clinical or statistically significant difference in the success rate of sentinel node biopsy (P = 0.22), the number of blue sentinel nodes harvested (P = 0.46), the concordance with radioactive sentinel nodes (P = 0.92), or the incidence of metastases (P = 0.87) when methylene blue tracer was compared to isosulfan blue. No adverse reaction to either blue dye was observed. In conclusion, intraparenchymal injection of methylene blue dye is a reliable tracer for the lymphatic system and nodal identification during sentinel node mapping for breast cancer. It is safe, inexpensive, and readily available.