The use of isotope injections in sentinel node biopsy for breast cancer: are the 1- and 2-day protocols equally effective?

Sentinel lymph nodes are mapped using (99m)Technetium, injected on day of surgery (1-day protocol) or day before (2-day protocol). This retrospective cohort study compares efficacy between the two protocols. Histopathology for all unilateral sentinel lymph node biopsies (March 2012-March 2013) in a single centre were reviewed. Number of sentinel lymph nodes, non-sentinel lymph nodes and pathology was compared. 2/270 (0.7 %) in 1-day protocol and 8/192 (4 %) in 2-day protocol had no sentinel lymph nodes removed (p = 0.02). The median (range) number of sentinel lymph nodes removed per patient was 2 (0-7) and 1 (0-11) in the 1- and 2-day protocols respectively (p = 0.08). There was a trend for removing more non-sentinel lymph nodes in 2-day protocol [1-day: 52/270 (19 %); 2-day: 50/192 (26 %), p = 0.07]. Using 2-day, sentinel lymph node identification failure rate is higher, although within acceptable rates. The 1 and 2 day protocols are both effective, therefore choice of protocol should be driven by patient convenience and hospital efficiency. However, this study raises the possibility that 1-day may be preferable when higher sentinel lymph node count is beneficial, for example following neoadjuvant chemotherapy.