[Is sentinel lymph node mapping relevant for colon cancer?: a feasibility study]

Sentinel lymph node (sln) technique using blue injection is controversial for colon cancer. The aim of this study was to evaluate the feasibility and interest of sentinel node detection to identify the ultrastaging rate detecting occult nodal micrometastases missed on routine H&E examination.

During surgery blue dye was injected subserously around the tumor in 30 patients operated for a colon cancer. The first lymph nodes to turn blue were noted as sln. For each sln three examination levels were performed; if no tumor was detected by H&E examination, a cytokeratine immunohistochemistry study was performed.

For each case, one or more sln were found (100%). The median number of lymph nodes examined and of sln found was, respectively, 23 (range 10-55) and 2 (1-4). There were 21 pN0 tumors, among which we found two cases (9%) with a micrometastasis and one case of isolated tumor cells detected, resulting in a 14% (3/21) ultrastaging for pTxN0. The sln was positive in five patients out of nine with a N+ disease.

Sln detection was a successful technique when there was no evident lymph node involvement, no primary large lesion or no associated liver metastasis. Focused examination of the sln identified 10-20% of additional ultrastaging disease for staged pT1, 2, 3N0M0 tumor. This may have an important implication for follow-up and adjuvant treatment in future protocols.