BACKGROUND - In sentinel lymph node (SLN) biopsy for breast cancer, many centers use same-day preoperative injection of technetium 99mTc-labeled sulfur colloid and intraoperative injection of blue dye for localization of SLNs. Same-day sulfur colloid injections can be problematic because of the variability in sulfur colloid migration times, which can lead to ineffective use of operating room time, and low SLN-to-background radioactivity ratios. We examined the utility of day-before-surgery injections of high dose 99mTc-labeled sulfur colloid injections.
METHODS - The day before surgery, high-dose 99mTc-labeled sulfur colloid was injected peritumorally, and a lymphoscintigram was obtained. Intraoperatively, after injection of blue dye, a gamma probe was used to localize SLNs. Nodes that were stained blue or were highly radioactive were considered SLNs and were removed.
RESULTS - Lymphoscintigraphy demonstrated drainage in 107 patients (91%). Transcutaneous localization of the SLN was possible in 104 patients (89%). In three patients, all of whom had no drainage demonstrated on lymphoscintigraphy, no SLN was identified at surgery (97.5% success rate for SLN identification). A mean of 2.3 SLNs per patient were identified. Twenty-five patients (21%) had at least one histologically positive SLN. In 23 of these patients, the positive SLN was the SLN with the most radioactivity, and in the remaining two patients, the positive SLN was both blue-stained and hot.
CONCLUSION - Day-before-surgery injection of high-dose 99mTc-labeled sulfur colloid results in high rates of transcutaneous and intraoperative identification of SLNs. The delay between injection and surgery did not appear to promote significant passage of sulfur colloid to second-echelon nodes.