[Current status of sentinel lymph node-based nodal ultrastaging in colorectal cancer]

Metastasis to the regional lymph nodes is an important prognostic factor in colorectal cancer, and nodal evaluation is essential for accurate staging. In colorectal cancer, the aim of evaluating sentinel lymph nodes (SLNs) is the selection of patients for adjuvant therapy and the detection of aberrant lymphatic drainage patterns, leading to modification of the initial therapeutic plan. In a review of the literature, tracer, technique, tumor-related factors (location and size of tumor, T stage, status of lymph node metastasis), neoadjuvant chemoradiation therapy, and body mass index were important factors in the accurate diagnosis of SLNs in colorectal cancer. In recent multicenter SLN trials, ultrastaging has been possible in 10-38% of NO colon cancer patients. Most recently, the trial conducted by Bilchik et al., which investigated the prognostic significance of micrometastases in SLNs in colon cancer patients, found that all NO colon cancer patients with recurrence had positive SLN findings after reverse transcriptase-polymerase chain reaction (RT-PCR)-ultrastaging, whereas none of those with negative SLN findings in immunohistologic staining had recurrence, and there was only a significant correlation between recurrence and molecular markers in RT-PCR. However, further prospective multicenter trials are warranted to evaluate the ultimate clinical relevance of SLN diagnosis in colorectal cancer including anal cancer.