Lymphatic mapping improves staging during laparoscopic colectomy for cancer

Background: Recently, lymphatic mapping (LM) of the sentinel lymph node (SN ) has been coupled with ultrastaging methods to diagnose nodal micrometasta ses from colorectal cancer (CRC). We have developed a technique for LM at t he time of laparoscopic colon resection (LCR). Methods: Between August 1996 and February 2000, 11 patients with small earl y-stage CRC underwent laparoscopic LM and LCR. The primary tumor/polyp site was visualized through a colonoscope and either tattooed preoperatively wi th a carbon dye (India ink), or stained intraoperatively by peritumoral inj ection of isosulfan blue dye. Immediately after intraoperative injection of blue dye, efferent lymphatic channels were visualized through the laparosc ope and followed to the SN, Each blue-stained SN was marked with a suture o r clip. Results: In all 11 cases, laparoscopic LM identified between one and three SN draining the primary tumor. LM added similar to 15-20 min to the operati ng time. The SN correctly reflected the nodal status of the entire specimen in all cases. In the one node-positive case, micrometastases were found on ly in an SN and only after cytokeratin immunohistochemistry (CK-IHC), In fo ur cases, LM demonstrated unexpected primary lymphatic drainage that prompt ed an increase in the margins of resection. Conclusions: LM during laparoscopic colectomy for CRC may be useful to mark the primary tumor site and to demonstrate lymphatic drainage that can alte r the margins of resection, Focused examination of SN identifies occult mic rometastases that up-stage CRC.