Sentinel lymph node mapping in colorectal cancer: a feasibility study

Aims and background: Sentinel lymph node (SLN) biopsy is currently used and investigated in melanoma and in breast cancer. Its utility in gastrointestinal malignancies is still under debate. The prognosis of colorectal cancer patients is strongly related to the lymphatic involvement. The aim of this study was to evaluate the feasibility of SLN mapping in colorectal cancer and to assess its impact on pathological staging and treatment. Methods and study design: We injected blue dye in 11 colorectal cancer patients during surgery. After resection the tumor specimen was examined to identify blue-stained lymph nodes and these lymph nodes were sent separately to the pathologist. Routine hematoxylin-eosin examination was performed on all nodes (including blue ones). No other techniques (eg immunohistochemistry or PCR) were performed. Results: Sentinel lymph nodes were successfully identified in 10 of the 11 patients. We observed only one false negative result (10%) and the agreement between SLN and other lymph node status was 80% (8/10). One patient was upstaged: SLN was positive for metastases while the other lymph nodes were negative. Conclusions: Lymphatic mapping using patent blue dye is feasible in colorectal cancer. The identification of lymph nodal metastases by this technique led to upstaging of one patient, who may benefit from adjuvant therapy. These initial results prompt further investigation of this procedure as an accurate, minimally invasive staging approach in early colorectal cancer. We proceed with our study to evaluate the role of SLN mapping in colorectal cancer management.