Sentinel node biopsy (SNB) has become standard of care in early stage vulvar cancer. As the correlation of isotope count with the presence of metastases remains unclear, often several active nodes are excised per groin. This can result in increased morbidity in node-negative disease despite of SNB. In the current analysis we assess, whether resection of the hottest node could be sufficient to detect sentinel lymph node (SNL) metastasis.
All patients with primary vulvar cancer receiving a SNB with radioactive tracer at the University Medical Center Hamburg-Eppendorf between 2008 and 2015 were evaluated. The day before surgery, patients received four peritumoral intradermal deposits at 3, 6, 9 and 12 o’clock with an overall mean dosage of 85±12MBq99mTc–nanocolloid. Planar lymphscintigraphy was performed one hour after injection. Intraoperatively, a handheld gamma counter was used to identify the SNL.
145 patients with SNB were included; thereof 144 underwent bilateral SNB, resulting in 289 analyzed groins. A median of 2 (range 1-7) SNL per groin were removed. From 94/289 (32.5%) groins more than 2 SNL were excised. Median overall SNL isotope count was 1400. In 50 groins, a positive SNL was detected (unilateral in 38 patients, bilateral in 6). The median number of positive SNL per groin was 1 (range 1-4). The SNL with the highest isotope count carried metastases in 36/46 groins (78.3%; in 4 cases the highest count was unknown). In 10/46 (21.7%) positive groins, the SNL with the highest count was not the metastatic SNL (9/10 second highest count). Median count of these 12 SNL was 60% of the highest count with a range from 11.0% to 74.0%.
The highest isotope count does not reliably detect the positive SNL in vulvar cancer. To prevent mostly fatal groin recurrences, surgeons should continue to remove all SNL accumulating relevant radioactive tracer over minimal background activity.