Current Status and Challenges of Imaging-Based Diagnosis of Lymph Node Metastasis in Colon Cancer: The Lymph Node Committee of the Japanese Society for Cancer of the Colon and Rectum.

Background: Accurate pre-treatment evaluation of lymph node metastasis (LNM) in colon cancer is important for determining an optimal treatment strategy. This diagnosis is mainly performed using the size of lymph nodes visualized on CT, although morphological diagnosis is also used. Results: Meta-analyses of CT for diagnosis of LNM in colon cancer indicate unsatisfactory results, with pooled sensitivities of 71% and 74%, and pooled specificities of 67% and 54%. Our recent report also showed only moderate diagnostic performance, with pooled sensitivity of 66.7%, pooled specificity of 72.4%, and an AUC of the HSROC of 0.741. This is because strict positive criteria based on the size and morphology of visualized lymph nodes are difficult to establish, and currently there are limitations to determining treatment strategies based on imaging diagnosis. Diagnostic accuracy can be improved by setting individualized diagnostic criteria according to the purpose, considering underlying clinicopathological factors, and combining multiple metastasis-related factors. New diagnostic methods such as dual-energy CT and radiomics have also been explored. Unlike traditional diagnoses based on imaging findings, these methods quantify and evaluate parameters, and radiomics, in particular, allows detailed evaluation by quantifying high-dimensional features that are not visible. Conclusion: Further studies are required to improve diagnostic capabilities that will enable optimal treatment strategies for LNM in colon cancer.