Sentinel lymph node mapping technique in colon cancer.

Current conventional surgical and pathological techniques substantially understage colon cancer. This is evidenced by the fact that a significant subset of patients who are stage I and II at the time of colectomy return with distant metastases and ultimately succumb to the disease within the next 5 years. The identification of more nodes within a specimen and the detailed analysis of lymph nodes with advanced pathological techniques such as immunohistochemistry and reverse-transcriptase polymerase chain reaction (RT-PCR) can improve the staging of colon cancer, but are also associated with tremendous financial, time, and labor constraints. Sentinel lymph node (SLN) mapping has provided an avenue of staging colon cancer with high success rates and accuracy rates, while maintaining cost- and time-effectiveness. The ability to reproduce these results is dependent on adherence to the technical details of the procedure, and thereby providing the pathologist with the true SLNs, upon which the advanced pathological studies can be applied. We report our experience of SLN mapping for colon tumors in 209 patients, elaborating on the materials used, technical details, pitfalls, and results of the procedure. Our results show a success rate of 100% (209/209) and an overall accuracy rate for predicting positive or negative metastatic disease of 96.2% (201/209). Nodal metastases were identified in 46.2% (85/184) of patients with invasive disease (stage T1 to T4). The SLN was the exclusive site of metastases in 38.8% (33/85) of these patients, and the nodal disease was detected only as micrometastases in 22.4% (19/85). The skip metastases rate (false negatives) was 9.4% (8/85). SLN mapping is a powerful tool for accurate staging of colon cancer with a high success rate. The upstaging associated with this procedure may reveal disease that might otherwise go undetected by conventional surgical and pathological methods. Those patients who are upstaged can then benefit from adjuvant chemotherapy, which has been shown to improve survival of colon cancer patients with nodal disease by at least 33%.