Sentinel lymph node detection in oral cancer: a within-patient comparison between [99mTc]Tc-tilmanocept and [99mTc]Tc-nanocolloid
Inne J. den Toom, Rutger Mahieu, Rob van Rooij, Robert J.J. van Es, Monique G. G. Hobbelink, Gerard C. Krijger, Bernard M. Tijink, Bart de Keizer, Remco de Bree
Abstract
Abstract Purpose Sentinel lymph node (SLN) biopsy has proven to reliably stage the clinically negative neck in early-stage oral squamous cell carcinoma (OSCC). [ 99m Tc]Tc-tilmanocept may be of benefit in OSCC with complex lymphatic drainage patterns and close spatial relation to SLNs. Methods A prospective within-patient evaluation study was designed to compare [ 99m Tc]Tc-tilmanocept with [ 99m Tc]Tc-nanocolloid for SLN detection. A total of 20 patients with early-stage OSCC were included, who underwent lymphoscintigraphy with both tracers. Both lymphoscintigraphic images of each patient were evaluated for SLN detection and radiotracer distribution at 2–4 h post-injection. Results The injection site’s remaining radioactivity was significantly lower for [ 99m Tc]Tc-tilmanocept (29.9%), compared with [ 99m Tc]Tc-nanocolloid (60.9%; p < 0.001). Radioactive uptake in SLNs was significantly lower for [ 99m Tc]Tc-tilmanocept (1.95%) compared with [ 99m Tc]Tc-nanocolloid (3.16%; p = 0.010). No significant difference was seen in SLN to injection site ratio in radioactivity between [ 99m Tc]Tc-tilmanocept (0.066) and [ 99m Tc]Tc-nanocolloid (0.054; p = 0.232). A median of 3.0 and 2.5 SLNs were identified with [ 99m Tc]Tc-tilmanocept and [ 99m Tc]Tc-nanocolloid, respectively ( p = 0.297). Radioactive uptake in higher echelon nodes was not significantly different between [ 99m Tc]Tc-tilmanocept (0.57%) and [ 99m Tc]Tc-nanocolloid (0.86%) ( p = 0.052). A median of 2.0 and 2.5 higher echelon nodes was identified with [ 99m Tc]Tc-tilmanocept and [ 99m Tc]Tc-nanocolloid, respectively ( p = 0.083). Conclusion [ 99m Tc]Tc-tilmanocept had a higher injection site clearance, but at the same time a lower uptake in the SLN, resulting in an SLN to injection site ratio, which was not significantly different from [ 99m Tc]Tc-nanocolloid. The relatively low-radioactive uptake in SLNs of [ 99m Tc]Tc-tilmanocept may limit intraoperative detection of SLNs, but can be overcome by a higher injection dose.