Selection criteria for high risk and low risk groups of recurrence and metastasis in patients with primary colorectal cancer

Among 371 patients with primary colorectal cancer, 54 patients suffered from recurrence/metastasis (recurrence group) and 317 survived without recurrence for at least 5 years (non-recurrence group). The clinicopathological characteristics of the 2 groups were compared and occult neoplastic cells (ONCs) in the lymph node sinuses were detected by cytokeratin immunohistochemistry. There were significant differences of the following factors: venous invasion (v−) vs. (v+) for Dukes' A patients (p=0.0315); harvested lymph nodes (LN) ≤14 vs. ≥15 for Dukes' B patients (p=0.0388); (v−) vs. (v+) (p=0.0059), lymphatic invasion (ly−) vs. (ly+) (p=0.0435) for Dukes' A and B patients combined; D>n vs. D=n (p=0.0033), depth of tumor invasion ≤ss/a1 vs. ≥se/a2 (p=0.0329) for Dukes' C patients. When the detection of ≥3 ONCs was defined as positive, the sensitivity, specificity, PPV, and NPV were respectively 77%, 100%, 100% and 71% in Dukes' B patients, as well as 75%, 72%, 73% and 74% in Dukes' C patients. The high-risk groups for recurrence/metastasis were identified by the following criteria: (v+) and (ly+), ≤14 LN, and ONCs (+) of those with all factors for Dukes' A and B patients (selection rate, approximately 23.5%), while the criteria were D=n, ≥se/a2, and ONCs (+) of those with ≥2 factors for Dukes' C patients (selection rate; approximately 21.2-37.5%). These factors seem to be appropriate for separating patients into high-risk and low-risk groups of colorectal cancer recurrence/metastasis.