Injection of (99m)Tc-labeled sulfur colloid the day before operation for breast cancer sentinel lymph node mapping is as successful as injection the day of operation.

BACKGROUND: We investigated whether the timing of injection of (99m)Tc-labeled sulfur colloid (radiocolloid) significantly influenced the success of breast cancer sentinel lymph node (SLN) mapping. METHODS: Review of a prospective SLN database. Five hundred forty-six consecutive breast SLN mapping patients were analyzed. A dual radiocolloid/blue dye technique was used in all patients. RESULTS: The SLN identification rate was similar among those patients injected the day prior (100%) and those injected the day of operation (99%, P = 0.14). A "hot" SLN was identified in 99% of patients injected the day prior and in 97% (P = 0.17) injected the day of operation. The mean number of SLNs was greater among those injected the day prior (2.71) than among those injected the day of operation (2.33, P = 0.01). There were no differences in the rates of SLN metastases. CONCLUSIONS: Radiocolloid injection the day before operation is an acceptable and logistically advantageous technique for breast cancer SLN mapping.