Ex vivo sentinel lymph node "mapping" in colorectal cancer

Abstract

Background: The purpose of this study was to evaluate the feasibility and reliability of ex vivo sentinel lymph node mapping in patients with colorectal cancer.

Methods: In the period January-June 2006, 44 consecutive patients underwent curative surgery for colorectal cancer. In patients with colon and rectal cancer, 0.5-2 ml of Patent Blue Dye was injected submucosally. The injection sites where then gently massaged for 5 min.

Results: In 96% of the patients with colon cancer and 94% of the patients with rectal cancer, at least one sentinel lymph node was found. There were no patients with a false negative sentinel node. The sensitivity was 100% with a negative predictive value of 100%. In 19% of the patients with colon cancer and 18% of the patients with rectal cancer the sentinel node was the exclusive site of lymph node metastases. After additional sectioning and staining, 7 of the 23 patients (30%) with a Dukes B colorectal cancer were upstaged.

Conclusion: The technique of ex vivo sentinel lymph node mapping is technically feasible with high sensitivity, high negative predictive value and a high rate of upstaging. The next step is to investigate, if detection of micro-metastases is associated with decreased survival and/or increased local recurrence rates.