Comparative research on 99m Tc-Rituximab and 99m Tc-sulfur colloid in sentinel lymph node imaging of breast cancer

Background 99m Tc-Rituximab is a new specific radiopharmaceutical that binds to the CD20 receptor which is highly expressed on the surface of B cells. We conducted a study in which 99m Tc-Rituximab was compared with filtered 99m Tc-sulfur colloid (fTcSC) for sentinel lymph node (SLN) detection in patients with breast cancer. Method The study is divided into three parts. 1. Initially, 25 patients were selected for an internal controlled trial to received both 99m Tc-Rituximab and fTcSC, the interval time is separated by ≥2 days. 2. Then, 91 patients were selected for a randomized controlled trial (41 and 50 patients in the 99m Tc-Rituximab and fTcSC groups, respectively). All patients were administered either agent at the 6- and 12-o’ clock positions by subareolar injection technique. SLN mapping was then performed 2 h after injection. 3. Serial dynamic images were further acquired for 2 h in 31 patients (22 and 9 patients from 99m Tc-Rituximab and fTcSC cohorts, respectively). Results The identification rate of lymphoscintigraphy and SLNB in all and axilla regions for 99m Tc-Rituximab and 99m Tc-SC were 98.5% vs 98.7, 100% vs 98.4%, respectively. The mean number of SLNs identified by 99m Tc-Rituximab and fTcSC was respectively 2.72 and 3.28, with a significant difference of P = 0.013 (paired sample t-test). The difference exists in the internal mammary and clavicular area, not in the axillary. The mean number of axillary sentinel lymph node biopsy (SLNB) for 99m Tc-Rituximab and fTcSC was 2.95 vs 3.14, respectively, and no significant difference existed. 99m Tc-Rituximab also exhibited a significantly faster injection site clearance rate when compared with fTcSC (0.193 ± 0.057 h − 1 vs 0.021 ± 0.007 h − 1 , respectively). Conclusion No significant difference was observed in identification rate and number of axillary SLN imaging and SLNB, between the two tracers. Compared to fTcSC, 99m Tc-Rituximab based imaging demonstrated a fewer number of secondary lymph nodes and had faster injection site clearance rate. Trial registration www.chictr.org.cn, ChiCTR1900024990 (retrospectively registered August 6, 2019).