Local recurrence and occult neoplastic cells in the extranodal fat of dissected lymph nodes in patients with curatively resected primary colorectal cancer

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.