Published online Jan 14, 2015. doi: 10.3748/wjg.v21.i2.556
Peer-review started: May 19, 2014
First decision: June 10, 2014
Revised: June 30, 2014
Accepted: July 25, 2014
Article in press: July 25, 2014
Published online: January 14, 2015
AIM: To assess the role of computed tomography (CT) and magnetic resonance imaging (MRI) and establish imaging criteria of lymph node metastasis in early colorectal cancer.
METHODS: One hundred and sixty patients with early colorectal cancer were evaluated for tumor location, clinical history of polypectomy, depth of tumor invasion, and lymph node metastasis. Two radiologists assessed preoperative CT and/or MRI for the primary tumor site detectability, the presence or absence of regional lymph node, and the size of the largest lymph node. Demographic, imaging, and pathologic findings were compared between the two groups of patients based on pathologic lymph node metastasis and optimal size criterion was obtained.
RESULTS: The locations of tumor were ascending, transverse, descending, sigmoid colon, and rectum. One hundred and sixty early colorectal cancers were classified into 3 groups based on the pathological depth of tumor invasion; mucosa, submucosa, and depth unavailable. A total of 20 (12.5%) cancers with submucosal invasion showed lymph node metastasis. Lymph nodes were detected on CT or MRI in 53 patients. The detection rate and size of lymph nodes were significantly higher (P = 0.000, P = 0.044, respectively) in patients with pathologic nodal metastasis than in patients without nodal metastasis. Receiver operating curve analysis showed that a cut-off value of 4.1 mm is optimal with a sensitivity of 78.6% and specificity of 75%.
CONCLUSION: The short diameter size criterion of ≥ 4.1 mm for metastatic lymph nodes was optimal for nodal staging in early colorectal cancer.
Core tip: This study is the first study on the imaging criterion of lymph node metastasis in early colorectal cancer. The results suggest that the detection rate and the size of lymph nodes (LNs) were significantly higher in patients with pathologic nodal metastasis. The optimal size criterion for LN metastasis was ≥ 4.1 mm in early colorectal cancer.