Background: In squamous cell vulvar cancer, sentinel node biopsy is accepted as standard treatment in well-defined patient groups and has reduced surgical morbidity considerably. Currently, due to the lack of evidence, it cannot be offered to patients with tumors of 4 cm diameter or greater or with multifocal tumors, or in local recurrences.

Primary objective: This study is primarily a pilot and feasibility trial, aiming to evaluate if the prerequisites concerning detection rate and negative predictive value are satisfactory before the implementation of a multinational trial.

Study hypothesis: Sentinel node biopsy has an acceptable negative predictive value and detection rate in the study cohort.

Trial design: This study is planned as a prospective, national, multicenter interventional trial. Participating patients will undergo a sentinel node biopsy in addition to an inguinofemoral lymphadenectomy.

Inclusion and exclusion criteria: Inclusion criteria: for women in group 1, a primary tumor ≥4 cm in diameter; in group 2, a multifocal primary tumor; in group 3, a local recurrence without previous inguinofemoral lymphadenectomy or radiation to the groins; in group 4, a local recurrence, with previous inguinofemoral lymphadenectomy and/or radiation to the groins.

Primary endpoint: The primary endpoints are the detection rate and the negative predictive value of the sentinel node procedure.