Lymphatic mapping and sentinel node analysis to optimize laparoscopic resection and staging of colorectal cancer: an update.

BACKGROUND: Laparoscopic colectomy for colorectal cancer (CRC) has been criticized because of the potential for inadequate nodal dissection and incomplete staging. Lymphatic mapping (LM) and sentinel lymph node (SLN) analysis can improve the accuracy of staging in open colectomy, but its utility during laparoscopic colectomy is unknown.
METHODS: Between 1996 and 2002, 30 patients with clinically localized colorectal neoplasms or premalignant polyps underwent subserosal or submucosal injection of isosulfan blue dye via a colonoscope, via a percutaneously inserted spinal needle, or through a hand port. Blue-stained lymphatics were visualized through the laparoscope and followed to the SLN, which was tagged. The colectomy was completed in standard fashion. All lymph nodes were stained by hematoxylin and eosin, and multiple sections of each SLN were examined by immunohistochemical (IHC) staining using cytokeratin antibody.
RESULTS: An SLN was identified laparoscopically in all patients. The SLN accurately predicted the tumor status of the nodal basin in 93% of cases. In 8 cases (29%), an unexpected lymphatic drainage pattern altered the extent of mesenteric resection, and in 4 cases (14%), tumor deposits were identified only by IHC and limited to the SLN.
CONCLUSIONS: This study, which updates a preliminary report (Am Surg. 2002;68:561-565) confirms that SLN mapping during laparoscopic colon resection can alter the margins of resection and may improve staging by allowing a focused pathologic examination of the SLN, although direct comparison with the "gold standard" of open CRC with adequate lymphadenectomy will be required. Better ultrastaging of CRC lymph nodes may more accurately assign patients to prospective protocols to assess the significance of nodal micrometastases or isolated tumor cells.