Feasibility of sentinel node detection in renal cell carcinoma: a pilot study

Lymphatic drainage from renal cell carcinoma is unpredictable and the therapeutic benefit and extent of lymph node dissection are controversial. We evaluated the feasibility of intratumoural injection of a radiolabelled tracer to image and sample draining lymph nodes in clinically non-metastatic renal cell carcinoma. Eight patients with cT1-2 cN0 cM0 (<6 cm) renal cell carcinoma prospectively received percutaneous intratumoural injections of 99mTc-nanocolloid under ultrasound guidance (0.4 ml, 225 MBq at one to four intratumoural locations depending on tumour size). Lymphoscintigraphy was performed 20 min, 2 h and 4 h after injection. After the delayed images a hybrid SPECT/CT was performed. SPECT was fused with CT to determine the anatomical localization of the sentinel node. Surgery with sampling was performed the following day using a gamma probe and a portable mini gamma camera. Eight patients, seven with right-sided renal cell carcinoma, were included with a mean age of 55 years (range: 45-77). The mean tumour size was 4 cm (range: 3.5-6 cm). Six patients had sentinel nodes on scintigraphy (two retrocaval, four interaortocaval, including one hilar) with one extraretroperitoneal location along the internal mammary chain. All nodes could be mapped and sampled. In two patients no drainage was visualized. Renal cell carcinomas were of clear cell subtype with no lymph node metastases. Sentinel node identification using preoperative and intraoperative imaging to locate and sample the sentinel node at surgery in renal cell carcinoma is feasible. Sentinel node biopsy may clarify the pattern of lymphatic drainage and extent of lymphatic spread which may have diagnostic and therapeutic implications. (orig.)