Objectives We sought to characterize our experience with SLN biopsy in patients with vulvar cancer, focusing on the modality of SLN detection.

Methods We performed a retrospective analysis of patients who underwent inguinofemoral SLN biopsy for vulvar cancer at Memorial Sloan Kettering Cancer Center from 1/1/2000–4/1/2019. An “at-risk groin” was defined as the inguinofemoral lymph nodes from either the right or left groin for which SLN biopsy was performed. Pearson’s Chi-Squared test was used for comparison of categorical variables.

Results 160 patients were included, representing 265 at-risk groins. Demographic and pathologic features are summarized in the table 1. Patients underwent mapping with a combination of Technicium-99 radiocolloid injection (TC-99), blue dye injection, or near-infrared imaging with indocyanine green (ICG) injection. SLN detection rate, irrespective of modality, was 96.2%. TC-99 + Blue dye detected SLNs in 91.8% of groins, and TC-99 + ICG detected SLNs in 100% of groins (p = 0.157). The use of ICG alone resulted in an SLN detection rate of 96.3% (26/27). Among the 110 groins that underwent mapping with TC-99 and blue dye, 4 patients mapped with TC-99 alone (3.6%). Among the 96 groins that underwent mapping with TC-99 and ICG, 14 mapped with ICG alone (14.6%).

Conclusions The use of ICG for inguinofemoral SLN mapping has increased over the past decade and is associated with the highest rates of SLN mapping of any modality.