[Prognostic significance of lymph node micrometastasis in colorectal cancer].

BACKGROUND & OBJECTIVE: There have been many controversies about the prognostic significance of lymph node micrometastasis. The aim of this study was to characterize the prognostic significance of lymph node micrometastasis of colorectal cancer.

METHODS

Specimens of curative resection between 1988 and 2001 were collected from The Affiliated Hospital of Jianghan University Medical and Life Science College. All 80 patients (30 cases of rectal cancer, 50 cases of colon cancer) had complete examination data. A total of 3869 lymph nodes (48.36 per case) were found by clearing fat method. The interrupted serial 4-micron sections, routine hematoxylin and eosin staining and immunohistochemistry methods were used to detect the lymph node metastasis and micrometastasis (small tumor cells cluster diameter <or=0.2 mm or tumor cells detected in the lymph nodes <or=50). All data was processed using Cox univariate analysis and Spearman rank correlation analysis (SAS 8.1 software).

RESULTS

Metastases were found in 232 (6%) lymph nodes examined and micrometastases in 39 (1.01%) lymph nodes. In the cases of rectal cancer, a highly significant correlation was found between lymph node metastases and mortality by univariate analysis (Chi(2)=9.94, P=0.0016) and micrometastases by Spearman rank correlation analysis (r=0.44, P=0.016). In the cases of colon cancer, a highly significant correlation was found among lymph node metastases (Chi(2)=9.52, P=0.002), UICC lymph node staging (Chi(2)=5.73, P=0.0167) and mortality by univariate analysis. And Spearman rank correlation analysis demonstrated a significant correlation between lymph node micrometastasis and Dukes' lymph node staging (r=0.314, P=0.008).

CONCLUSION

Lymph node micrometastasis possesses considerable value for prognosis of colorectal cancer, but should be used in integration with other indicators.