Correlation of isotope count with sentinel node positivity in vulvar cancer

Aim:

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 SNL metastasis.

Material and methods:

Patients with primary vulvar cancer receiving a SNB with radioactive tracer at the University Medical Center Hamburg-Eppendorf between 2008 and 2015 were evaluated.

Results:

145 patients with SNB were analysed; thereof 144 underwent bilateral SNB, resulting in 289 analyzed groins. A median of 2 SNL per groin were removed. From 94/289 (32.5%) groins more than 2 SNL were excised. Median overall SNL isotope count was 1400 counts per minute (cpm). In 50 groins, a positive SNL was detected. The median number of positive SNL per groin was 1 (range 1 – 4). The SNL with the highest isotope count carried metastases in 78.3% (36/46). In 10/46 positive groins, the SNL with the highest count was not the metastatic SNL (9/10 second highest count). Median count of these 10 SNL was 60% of the highest count with a range from 11.0% to 74.0%.

Conclusions:

The highest isotope count does not reliably detect the positive SLN in vulvar cancer. To prevent mostly fatal groin recurrences, surgeons should continue to remove all SLN accumulating relevant radioactive tracer over background activity.