Background: Although the technique of sentinel lymph node (SLN) biopsy in breast cancer is not fully standardized, an increasing number of centers map the SLN by using radioisotope supplemented by blue dye, and most have injected isotope on the day of surgery. Here we directly compare the results of same-day and day-before isotope injection in a large series of breast cancer patients having SLN biopsy with our mature technique.
Methods: Starting with our 961st SLN procedure for breast cancer, 1320 consecutive patients had SLN biopsy after the injection of unfiltered 99mTc-labeled sulfur colloid given as a single-site, low-volume (0.05 ml) intradermal injection: 933 on the day of surgery (1-day protocol) and 387 on the day before (2-day protocol). All had intraparenchymal injection of blue dye.
Results: The two groups were comparable in age, tumor location, histopathologic characteristics, and number of SLNs identified. LSG taken at 2 hours in the 2-day protocol was positive more often than LSG performed at 30 minutes in the 1-day protocol, and nonaxillary sites of lymphatic drainage were seen in <1% of each group. Absolute isotope counts and the ratio of SLN to axillary background counts were similar. Isotope localization of the SLN succeeded in a comparable fraction of patients, as did SLN identification overall.
Conclusions: The results of SLN mapping with same-day and day-before injection of radioisotope are virtually identical. The logistical advantages of day-before injection do not compromise the success of the procedure.