Prognostic value of the detection of lymph node micrometastases in colon cancer.

INTRODUCTION AND

objectivesA study is made of the clinical repercussions of occult metastases-micrometastases (MMs+)-or isolated tumour cells (ITCs+) in the lymph nodes of patients with stage IIA and IIB colon adenocarcinoma initially considered as corresponding to N0. MATERIAL AND

methodsA retrospective study of 39 patients with stage IIA and IIB (T3-T4 N0 M0) colon adenocarcinoma, subjected to similar surgical and adjuvant chemotherapy treatment, with long and careful follow-up (minimum: 5 years, mean: 81.7 months) was performed on their previously resected lymph nodes, with the aid of new histological and immunohistochemical (cytokeratin) sections, in order to detect MMs or ITCs. Disease-free survival (DFS) and global survival (GS) in the two groups (patients with MMs+ or ITCs+ vs. patients without MMs or ITCs) were compared at 5 years based on the corresponding Kaplan-Meier survival curves, with the Breslow test.

resultsA total of 382 lymph nodes from the 39 patients (mean: 9.8; standard deviation: 6.09) were revised. MMs+ were detected in 2 cases and ITCs+ in 2 more cases on the Cytokeratin study. GS of the whole series at 5 years was 89.74% (35 patients alive) with a DFS at 5 years of 79.49% (31 patients free of disease), but the 2 cases with MMs+ were dead at 5 years, with high statistical differences between both groups (MMs+/MMs-) (p<0.0001). When comparing the group of MMs+/ITCs+ patients and the group of MM-/ITCs- patients, the DFS and GS times at 5 years were higher in the MMs-/ITCs- group (p=0.0692 and p=0.006 respectively).

conclusionsAlthough the incidence of MMs+ or ITCs+ in the examined lymph nodes was low, the presence of MMs is related to a dramatic reduction in GS and DFS at 5 years. We encourage a detailed histological study of lymph nodes resected in patients with deep penetrating colon tumours in order to assure a pN0 status.