The impact of radiopharmaceutical particle size on the visualization and identification of sentinel nodes in breast cancer

Objectives The aim of this study was to compare the success rate in lymphatic mapping and sentinel node biopsy in breast cancer using two radiopharmaceuticals. Methods The study included 119 breast cancer patients who underwent lymphoscintigraphy after a single intratumoral injection of 99m Tc-labelled human albumin colloid with a particle size of 0.2-3 μm (Albu-Res) (large particle group) and 119 pair-matched control patients who underwent lymphoscintigraphy using 99m Tc-labelled albumin colloid with a particle size of <80nm (Nanocoll) (small particle group). The dose of the tracer was used as the matching factor. Results Lymphoscintigraphy showed sentinel nodes in the axilla in 101 patients (85%) in the large particle group and in 104 patients (87%) in the small particle group. The mean number of visualized nodes in the axilla was 1.7 in the small particle group and 1.3 in the large particle group (P < 0.05). No radioactive nodes were found in the axilla during the operation in 22 patients (18%) in the small particle group and 11 patients (9%) in the large particle group (P < 0.06). Patients who avoided axillary clearance had a similar number of harvested radioactive nodes irrespective of the particle size of the tracer. Conclusions It can be concluded that the success rate in the identification of axillary sentinel nodes may be higher when using the smaller particles, despite the similar visualization rate in lymphoscintigraphy. The number of harvested radioactive nodes was not affected by the particle size of the tracer in patients who avoided axillary clearance.