Intraoperative sentinel node identification and sampling in clinically node-negative renal cell carcinoma: initial experience in 20 patients.

PURPOSE: To apply single-photon emission computed tomography (SPECT) in combination with computed tomography (CT) for preoperative identification of sentinel lymph nodes (SNs) and to investigate surgical feasibility and safety of intraoperative sampling.
METHODS: A retrospective combined interim analysis of 20 patients from two prospective trials who underwent injection of 99mTc-nanocolloid into the renal tumour for preoperative identification of SN with SPECT/CT and subsequent removal of the tumour and intraoperative sampling using a gamma probe and portable camera. Lymphadenectomy was completed locoregionally. Surgical approach, time, blood loss, intraoperative yield, Clavien complications and anatomical location of SN in correlation with preoperative imaging were evaluated.
RESULTS: SPECT/CT detected SN in 14/20 patients (70%), including 4 patients with non-visualisation on planar lymphoscintigraphy. Twenty-six SNs were seen: 17 para-aortic (including interaorto-caval), 4 retrocaval, 1 hilar, 1 celiac trunc, 1 internal mammary and 2 mediastinal and pleural. These latter 4 nodes were not harvested according to protocol. All other SNs, except for 2 weakly radioactive interaorto-caval nodes, were identified and excised with a mean additional time of 20 min. None of the removed SN and locoregional nodes was tumour-bearing.
CONCLUSIONS: Intraoperative SN identification and sampling in RCC with preoperative detection on SPECT/CT is surgically safe and feasible. SN from the kidney are mainly localised in the para-aortic region, but aberrant nodes receive direct drainage. Non-visualisation of SN appears in almost a third of the patients. Further studies are required to demonstrate whether accurate mapping of lymphatic drainage and extent of lymphatic spread may have diagnostic and therapeutic implications.