Visualization of the sentinel node in early-stage oral cancer: limited value of late static lymphoscintigraphy

Various lymphoscintigraphic imaging protocols exist for sentinel node (SN) identification in early-stage oral cancer. This study aimed to evaluate the clinical value of performing additional late lymphoscintigraphic imaging.

We retrospectively analysed early (directly following injection of 99mTc-Nanocoll) and late (2-4 h after injection) imaging results of 60 early-stage (T1-T2, cN0) oral cancer patients scheduled for SN procedure. Lymphoscintigraphic results of late imaging were categorized into: (a) no visualization of additional hotspots considered to be SNs; (b) additional hotspots visualized that are considered to be SNs and (c) hotspots visualized only during late imaging. Histopathological results of the harvested SNs were related to the corresponding hotspot.

In all patients (n=60) lymphoscintigraphy was able to visualize a hotspot that was identified as an SN. In 51/60 (85%) patients, early imaging was able to visualize at least one hotspot, whereas in 9/60 (15%) patients, mostly with oral cavity tumours other than mobile tongue and floor-of-mouth tumours, only late imaging was able to visualize hotspots. In 14/51 (27%) patients, late imaging resulted in additionally visualized hotspots marked as SNs, resulting in a more extensive surgical procedure. These additionally removed SNs appeared to be of no clinical relevance, as all SNs identified during early imaging correctly predicted whether the neck was positive or negative for cancer.

Results of this study indicate that additional late lymphoscintigraphic imaging should be performed only in selected cases.