Abstract P1-01-17: Sentinel node biopsy for breast cancer: Intraoperative injection of radiocolloid

Abstract

Abstract INTRODUCTION. Preoperative injection of radiocolloid for axillary sentinel node biopsy for breast cancer is visibly uncomfortable for many patients. We sought to determine whether injection of the radiocolloid once the patient has been anesthetized would be reliable for sentinel lymph node identification when compared to preoperative injection. METHODS. A cohort of patients with breast cancer who underwent intraoperative injection of radiocolloid was compared to those who received their injection preoperatively. All injections employed 1mCi 0.5 ml of filtered (0.22 micron) Tc-99m sulfur colloid. All operative surgeons directed injections into the retroareolar tissue; some also intradermally directly over the tumor. RESULTS. 904 sentinel node biopsy procedures were performed in the six years study period. 759 sentinel node biopsies were analyzed, 664 with preoperative injection of radiocolloid for localization and ninety-five with intraoperative injection. The average age of the patients was 56.8 years: 57.3 years in the preoperative injection group and 53.8 years in the intraoperative injection group. 753 of the 759 patients were women. Sentinel Node Identification. The overall sentinel lymph node identification rate was similar for the two groups: 94.1% for the preoperative injection group and 93.5% for the intraoperative injection group (P = NS). The identification rate remained equivalent for both groups when analyzed by T stage of the tumor. Similarly, the average number of lymph nodes removed did not differ between preoperative vs. intraoperative injection: 2.66 nodes and 2.55 nodes, respectively. Sentinel Node Positivity. The overall rate of positive sentinel nodes was also similar for the two groups, 24.7% for the preoperative injection group and 26.4% for the intraoperative injection group (P = NS). When analyzed by T stage, the positivity rate remained similar and not statistically significant. T1 tumors were 21.6% positive in the preoperative group versus 23.9% in the intraoperative group, and T2 tumors were 40.1% vs. 37.0%, respectively. DISCUSSIONS. Our sentinel lymph node identification rate of 93.5% for the intraoperative injection group appears similar to that of the published literature (96-100%). Our study also showed no statistical difference in positive sentinel node biopsy between preoperative injection (24.7%) and intraoperative injection (26.2%) and is comparable to that of others When analyzed by T stage, our study had 23.9% positive sentinel node biopsies for T1, and 37% for T2 with intraoperative injection. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-01-17.