This study was designed to examine the relationship between occult neoplastic cells (ONCs) inside and outside harvested lymph nodes (intranodal/extranodal ONCs) and local recurrence in 30 patients who underwent curative resection of primary colorectal cancer. Among 10 patients with colon cancer (Dukes' A=1, Dukes' B=6 and Dukes' C=3), intranodal ONCs were positive in 1 patient (10.0%) and negative in 9 patients (90.0%), while extranodal ONCs were negative in all 10 patients (100.0%). There were no significant differences between the detection of intranodal or extranodal ONCs. Among 20 patients with rectal cancer (Dukes' A=4, Dukes' B=2 and Dukes' C=14), intranodal ONCs were positive in 5 (25.0%) and negative in 15 (75.0%), while extranodal ONCs were positive in 3 (15.0%) and negative in 17 (85.0%). There were no significant differences between the detection of intranodal or extranodal ONCs. These results suggest that patients with rectal cancer and extranodal ONCs should be followed-up carefully as a high-risk group for pelvic local recurrence. However, the prevalence of extranodal and intranodal ONCs was almost similar.

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