Sentinel lymph node mapping combined with targeted node excision and biopsy can improve staging of colorectal cancer and identify patients who do not need chemotherapy, according to an article in the June issue of Archives of Surgery.

"One third of patients with tumor-free lymph nodes have recurrences, and therefore, adjuvant chemotherapy may be beneficial in these patients," the authors wrote. "However, if all node-negative patients are treated, 70 percent will be subjected to unnecessary chemotherapy because surgery alone is curative. A better understanding of high-risk, node-negative patients and improved methods of lymph node evaluation are therefore needed."

Anton J. Bilchik, MD, PhD, John Wayne Cancer Institute, and colleagues studied 132 patients (63 men, 69 women; median age, 74 years) with stage I/II colon cancer between March 2001 and June 2005. During lymphatic mapping, blue dye was injected near the site of each primary tumor. The dye stained the sentinel lymph nodes. The tumor, sentinel nodes, and other lymph nodes in the region were then removed and examined.

Of the 132 participants, 33 (30 percent) had stage I cancer, 46 (41 percent) had stage II, and 32 (29 percent) stage III. Twenty-eight patients (23.6 percent) were classified at a more severe stage based on analysis of sentinel nodes.

The sensitivity of the lymphatic mapping/sentinel node procedure was 88.2 percent: 45 of 51 patients whose cancer had spread to the lymph nodes had tumors in their sentinel nodes. A false negative result occurred in six of 81 (7.4 percent) patients who were determined to be node negative. Eighteen percent of the sentinel nodes had tumors, compared with 6 percent of the other lymph nodes.

The results "suggest that lymphatic mapping and sentinel lymph node techniques are feasible and accurate in colon cancer," the authors concluded. "The improved risk stratification afforded by standardization of both surgical and pathological techniques may improve the selection of patients for chemotherapy, thereby avoiding the unnecessary toxic effects and expense for those cured by surgery alone."