The accuracy of the sentinel node procedure after excision biopsy in squamous cell carcinoma of the vulva

Abstract

Introduction Restricting inguinofemoral lymphadenectomy to patients with malignant nodes would reduce treatment-related morbidity in vulval cancer patients. A prospective study was conducted to determine the diagnostic accuracy of the Sentinel Lymph Node (SLN) procedure in vulval cancer patients referred following either diagnostic or excision biopsy. Methods Patients with clinical stage I and II squamous cell carcinoma of the vulva underwent SLN identification with peri-scar/lesional injection of 99mTechnetium-labelled nanocolloid (pre-operative lymphoscintigraphy and intra-operative use of a hand-held probe) and intra-operative blue dye. Radical excision of the vulval tumour or scar and formal inguinofemoral lymphadenectomy was then performed as necessary. SLN were processed separately and further examined at multiple levels to exclude micrometastases (H&E/cytokeratin staining) if negative on routine analysis. Clinical follow-up was carried out to identify and treat recurrences or treatment-related morbidity. Results Thirty-two women took part. Fifteen were referred following excision biopsy and seventeen following diagnostic biopsy of their primary vulval tumour. One or more SLN was successfully detected intra-operatively in 31 patients (97%) and 45 groins. An SLN could not be identified intra-operatively in one case (re-excision of scar). On average, more SLN were identified in patients with their primary vulval lesion in situ compared with those whose tumour had previously been excised (2.6 vs. 1.8, p = 0.03). Midline tumours were more likely (15/17) than lateral tumours (1/15) to have bilateral SLN identified pre-operatively. Two patients with midline tumours previously excised had unilateral SLN. Seven patients (23%) and ten groins had inguinofemoral lymph node metastases. The SLN procedure correctly identified inguinofemoral metastases in six patients (nine groins). In one case (midline tumour, re-excision of scar) the sentinel node was positive on one side but false negative on the other. Conclusions The SLN procedure may be used to identify malignant groins in selected patients with vulval cancer. The extent to which previous vulval surgery might influence the accuracy of the SLN procedure deserves further investigation.