The Risk of Contralateral Non-sentinel Metastasis in Patients with Primary Vulvar Cancer and Unilaterally Positive Sentinel Node

Background: In patients with primary vulvar cancer and bilateral sentinel lymph node (SLN) biopsy, bilateral complete inguino-femoral lymphadenectomy (LAE) is recommended, even in cases with only unilaterally positive SLN by most guidelines. The risk of contralateral non-SLN metastasis is unclear. Methods: All patients with primary vulvar cancer receiving an SLN dissection with radioactive tracer ± blue dye at the University Medical Center Hamburg-Eppendorf between 2001 and 2013 were retrospectively evaluated. Median follow-up was 33 months. Results: A total of 140 patients were included; 124 with bilateral and 16 with unilateral SLN dissection. A median number of two SLNs (range 1–7) per groin were dissected. Overall, 53 (53/140, 37.9 %) patients received a complete inguino-femoral LAE, 41 of whom (77.4 %) had previously presented with a positive SLN (33 unilaterally, 8 bilaterally). Of the 33 patients with unilaterally positive SLN, 28 (84.9 %) underwent complete bilateral inguino-femoral LAE despite a contralateral negative SLN. Of these patients, none presented a contralateral non-SLN metastasis (0/28, 0 %) in full dissection; however, one developed groin recurrence in the initially SLN-negative, fully dissected groin after 19 months (1/28, 3.6 %). Conclusion: In case of bilateral SLN biopsy for clinically node-negative disease and only unilaterally positive SLN, the risk for contralateral non-SLN metastases appears to be low. These data support the omission of contralateral LAE to reduce surgical morbidity.