Preliminary Study Of Sentinel Lymph Node Biopsy In Colorectal Cancerand Detection Of Micrometastasis In Sentinel Lymph Node

Objective To evaluate the feasibility of sentinel lymph node (SLN) biopsy with carbon nanoparticles (CNP) and 99mTc sulfur colloid (TSC) for colorectal cancer (CRC). To evaluate the value of immunohistochemistry (IHC) and quantitative Real Time PCR (QRT-PCR) for detection micrometastasis in SLN.Methods 22 patients who underwent radical resection of a primary colorectal cancer were enrolled. During operation, SLN mapping was performed with CNP combined TSC. All lymph nodes were stained with Hematoxylin eosin staining (HE). SLNs, when negative by routione HE staining, were further analyzed with CK20 immunohistochemistical staining. SLN tissue from 20 patients were analyzed with QRT-PCR.Results SLNs were detected in 20 of 22 patients with a successful detection rate of 90.91%. The number of SLNs ranged from 1 to 4,with a mean value of 1.750.97 per case.The diagnostic sensitivity,accuracy,predicting negative value and false-negative rate were 70.00%,85.00%,76.92% and 30.00%.respectively. Between colon cancer and rectal cancer, no difference exists in sensitivity,accuracy,predicting negative value.Of 10 patients with SLNs being negative by HE staining, there were 2 patients detected micrometatastases by cytokeratin 20 IHC.Five of twenty patients were found high level CK20-mRNA in SLN tissue by QRT-PCR.Conclusions The SLN concept is validated in CRC. Combined-agent SLN mapping is a potential diagnostic method for predicting local lymph node metastasis in the patients with CRC.IHC and QRT-PCR can increase detection rate of micrometastasis in SLN. But the clinical value of difference of CK20-mRNA in SLN needs to be further studied.