Objective: The volume of radiotracer to be injected for sentinel node mapping is a controversial issue in breast cancer patients. In the current study, we evaluated the effect of radiotracer injection volume on the success rate of sentinel node mapping in early-stage breast cancer patients.
Materials and methods: A total of 383 patients with early-stage breast cancer (cN0) were included in the study. The patients received an intradermal injection of Tc-antimony sulfide colloid for sentinel node mapping. The volume of injection was 0.1 ml for 102 patients, 0.2 ml for 221 patients, 0.5 ml for 30 patients, and 1 ml for 30 patients. The detection rate of the sentinel nodes during surgery was compared between the different injection volume groups.
Results: The overall detection rate was 93.9%. Detection rates were 95.1, 95, 90, and 86.7% for 0.1, 0.2, 0.5, and 1 ml volumes, respectively, which did not show a statistically significant difference despite minimal decrease in detection at higher volumes (P=0.214). The time of sentinel node visualization was not statistically different between the studied groups either (P=0.65).
Conclusion: Increasing the volume of radiotracer in intradermal injections does not have a statistically significant effect on the sentinel node detection rate (despite minimal decrease in detection at higher volumes), nor on the time of sentinel node visualization. A low volume (0.1 ml) of radiotracer for intradermal injections can be as successful as higher volumes for sentinel node mapping with the added benefit of reduced pain from injections.