Introduction/Background Sentinel lymph node (SLN) biopsy is the recommended staging method for single vulvar tumors, <4 cm, without suspected groin metastasis.

The vulva has an ample lymphatic system and especially for midline tumors (tumors that cross midline), its drainage can be made to both groins. According to international guidelines, bilateral detection of SLN is recomended for midline tumors and, in case of unilateral detection, inguinofemoral lymphadenectomy should be performed on the opposite groin.

In an era of de-escalation surgery, should bilateral groin evaluation be mandatory for midline vulvar tumors?

Methodology Retrospective observational study (2005–2018) of midline squamous-cell vulvar tumors, fulfilling criteria for SLN biopsy. In our oncology center, we detect SLN by performing lymphocintigraphy and using dual-mapping technique (radioactive tracer and blue-dye). In case of unilateral detection we do not execute contralateral lymphadenectomy.

The aim of the study is to evaluate recurrence on the contralateral groin when SLN was negative. To accomplish this, the study-population was divided into two groups, according to SLN biopsy: 1) unilateral; 2) bilateral.

Results We included 34 cases with a median follow-up time of 37,5 (1–111) months. During surgery, the detection rate of the SLN was 100% and always in accordance with the previous lymphocintigraphy. Group 1 included 16 cases (47%) and SLN biopsy was negative in 13 cases (81,3%). There were 2 cases of groin recurrence, one of which on the opposite side of the previous SLN. Group 2 included 18 cases (53%) and SLN biopsy was negative in 13 cases (72,2%). There wasn´t any case of groin recurrence.

Conclusion SLN biopsy is a feasible staging technique and should be directed by previous lymphocintigraphy. Because vulvar cancer is rare, few cases were described, but our approach does not seem to increase the groin recurrence rate on the non-evaluated side. More studies are needed.

Disclosure Nothing to disclose