Clinical significance of lymph node micrometastasis in stage I and II colon cancer

Abstract

Purpose: A 25% rate of recurrence after performing complete resection in node-negative colon cancer patients suggests that their nodal staging is frequently suboptimal. Moreover, the value of occult cancer cells in tumor-free lymph nodes still remains uncertain. The authors evaluated the prognostic significance of the pathologic parameters, including the lymph node occult disease (micrometastases) detected by immunohistochemistry, in patients with node-negative colon cancer.

Materials and methods: The study included 160 patients with curatively resected stage I or II colon cancer and they were without rectal cancer. 2852 lymph nodes were re-examined by re-do hematoxylin and eosin (H-E) staining and immunohistochemical staining. The detection rates were compared with the clinicopathologic characteristics and with the cancer-specific survival.

Results: Occult metastases were detected in 8 patients (5%). However, no clinicopathologic parameter was found to be correlated with the presence of micrometastasis. Twenty patients developed recurrence at a median follow-up of 45.7 months: 14 died of colon cancer and 9 died from noncancer-related causes. Univariate analysis showed that lymphatic invasion and the number of retrieved lymph nodes significantly influenced survival, and multivariate analysis revealed that the stage, the number of retrieved lymph nodes and lymphatic invasion were independently related to the prognosis.

Conclusions: Inadequate lymph node retrieval and lymphatic invasion were found to be associated with a poorer outcome for node-negative colon cancer patients. The presence of immunostained tumors cells in pN0 lymph nodes was found to have no significant effect on survival, but these tumor were identified by re-do H-E staining. Maximal attention should be paid to the total number of lymph nodes that are retrieved during surgery for colon cancer patients.

Keywords: Colonic neoplasms; Immunohistochemistry; Lymphatic metastasis; Survival.

Fig. 1

Disease-free survival according to (A) the stage (stage I vs. stage II) and (B) the number of retrieved LNs (<12 vs. ≥12). Both parameters were found to be significantly associated with disease-free survival.

Fig. 2

Overall survival according to (A) the number of retrieved LNs (<12 vs. ≥12) and (B) lymphatic invasion (absent vs. present). Both parameters were found to be significantly associated with disease-free survival.