Significance of the immunohistochemical detection of lymph node micrometastases in stage II colorectal carcinoma.

BACKGROUND Survival results of stage II colorectal cancer patients have led to major efforts to identify the subset of patients at risk for disease relapse and adjuvant therapies benefit. Immunohistochemistry is being explored to detect undetectable microscopic lymph node micrometastases. MATERIAL AND METHODS A retrospective analysis of a 105 consecutive stage II colorectal cancer patients was performed. Two four-micres sections were obtained from each lymph node. These slides were stained with AE1-AE3 monoclonal antibodies against cytoskeleton using DAKO EnVision visualization system. Micrometastases were identified either as isolated cells or as well-defined glandular cell clusters with cytoplasm but not the nucleus stained with cytoskeleton antibodies. RESULTS 665 lymph nodes isolated from 105 patients were analyzed. Lymph nodes micrometastases were assessed in 26 out of the 105 patients. 42 (6.3%) out of 665 lymph nodes were infiltrated. Most of these metastases consisted of isolated cell cluster localized in marginal and interfollicular sinus of lymph nodes. The relapse rate was 23.1% among the patients with immunohistochemical detected lymph node micrometastes and 20.3% for the patients without lymph node involvement. This result lacked statistical significance (p = 0.759). DISCUSSION AE1/AE3 lymph node immunohistochemical staining in stage II colorectal cancer is an interesting biological phenomenon but it fails to identify patients at higher risk of relapse who deserve a more aggressive adjuvant attitude.