Objective: To study lymph node involvement and micro-metastasis of rectal cancer with large slice technique and tissue microarray.
Methods: Large slice technique, combined with tissue microarray,was used in pathologic study of 31 patients after total mesorectal excision (TME) for rectal cancer.
Results: Nine hundred and ninety- two lymph nodes were harvested and 148 were positive. More than 40% of positive lymph nodes were located in the outer layer of the mesorectum and in the same side of the mesorectum as the primary tumor was. Circumferential margin involvement was observed in 12 cases and correlated with the numbers of metastatic lymph nodes (Beta =1.166, P=0.041). Micrometastasis was found in 9 cases with negative pathological lymph nodes, but not correlated with tumor differentiation and stage (P> 0.05).
Conclusion: Large slice technique combined with tissue microarray facilitates the detection of lymph node involvement and micrometastasis. There is a predominance of lymph node metastasis in the outer layer and the same side of the mesorectum. Micrometastasis can be discovered in different stages of rectal cancer.