Radionuclide-guided sentinel lymph node mapping in urachal cancer

Abstract

Background. Urachal cancer gives metastases through the lymph nodes (LNs). No lymphadenectomy scheme in the case of this cancer exist, yet it is proposed as a staging procedure. An assessment of lymphatic outflow from the tumor site with the use of single-photon emission computed tomography/computed tomography (SPECT/CT) lymphangiography is possible for staging purposes. Objectives. To perform the mapping of the LNs draining the lymph from urachal cancer with the use of radioisotope-based technique and to propose the lymphadenectomy template in case of urachal cancer. Material and methods. A prospective study was conducted in 5 patients with urachal cancer. The 99m-technetium (Tc-99m)-nanocolloid was injected during a cystoscopy prior to the surgery. Lymphangiography was performed using SPECT/CT. A radioactive LNs analysis with the use of a hand-held gamma-ray detection probe was conducted during the surgery and the sentinel lymph node (SLN) biopsy procedure was performed. An additional lymphadenectomy containing the lymphatic basin of identified radioactive LNs was performed. Results. In all cases lymphatic outflow from the urachal tumor to the LNs was present. Preoperative SPECT/CT allowed detecting the activity of the radiotracer in the common iliac region in all the studied patients. In 3 cases, bilateral lymphatic outflow, and in 2 cases, unilateral lymphatic outflow was observed. All preoperatively visualized LNs were found and excised with the use of a gamma-ray detection probe during a lymphadenectomy. In all cases, SLNs did not contain metastases. Conclusions. Mapping of the LNs draining the lymph from urachal cancer with the use of radiotracer is possible. Lymphatic outflow in the case of this cancer can be both unilateral and bilateral. No recommendations about the extension of lymphadenectomy are proposed. We recommend individual assessment and treatment based on additional knowledge about lymphatic outflow. This allows for minimally invasive yet targeted treatment as an SLN basin lymphadenectomy.