Sentinel lymph node mapping for carcinoma of the colon: A pilot study

Sentinel lymph node (SLN) mapping has evolved into the standard of care for melanoma and may replace routine node dissection in the treatment of breas t cancer. There are few data evaluating sentinel node mapping in patients w ith cancer of the colon. This trial represents our initial experience with SLN mapping for carcinoma of the colon. SLN mapping was performed in 22 pat ients most of whom had biopsy-proven adenocarcinoma of the colon. One milli liter of isosulfan blue was injected with a 25-gauge needle into the subser osa at four sites around the edge of the palpable tumor. The SLN was identi fied visually and excised. A standard lymphadenectomy was then performed. T he SLN was analyzed with standard hematoxylin and eosin evaluation. Immunoh istochemical techniques for carcinoembryonic antigen and cytokeratin (Imm) were performed if the H&E was negative. The mapping added approximately 5 m inutes to the total operative time and no adverse reactions to the dye occu rred. A SLN was identified in 20 of 22 cases. In cases with negative lymph nodes the SLN was predictive of all the regional nodes by both H&E and Imm (14 of 14). In patients with positive lymph nodes the SLN was predictive in all cases (six of six). In one case the only node with disease was the SLN , and in this case the disease was identified by only Imm; thus this patien t was upstaged. SLN mapping is feasible and safe and can readily be perform ed in patients with colonic cancer. In conjunction with SLN mapping, Imm te chniques may upstage a subset of patients likely to be at increased risk fo r metastatic disease. Consequently SLN mapping of colon cancer should be ev aluated in large prospective trials.