Injection of 99mTc-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 99mTc-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.