Safety and technical success of methylene blue dye for lymphatic mapping in breast cancer

Background: We aimed to evaluate the safety and efficacy of methylene blue dye (MBD) for sentinel lymph node (SLN) mapping in breast cancer. Methods: A total of 398 patients undergoing 401 SLN biopsy procedures with MBD were retrospectively reviewed and divided into 3 groups based on dye concentration and location of dye injection. Technical success and complication rates were compared. Results: Overall technical success of SLN biopsy was 99.7%. Technical success of SLN mapping with MBD was lowest in the group receiving full strength dye in a peritumoral location (74%) and highest in the group that received very dilute MBD (1.25 mg/mL) in the subareolar location (92%, P = .004). The complication rate was highest in the first group (21%) and lowest in the latter (2%, P = .0003). Conclusions: Dilute MBD (1.25 mg/mL) successfully maps SLNs with very few complications.