Biochemical and clinical approaches in evaluating the prognosis of colon cancer

Colorectal adenocarcinoma is a common malignant neoplasm in the Western world. To achieve optimal treatment results, the risk estimation of recurrence should be as accurate as possible.

Tissue material from tumour and normal mucosa was taken from six patients and was analysed to screen aberrantly expressed genes using cDNA microarray. Selected up-regulated genes were chosen for further analysis by immunohistochemistry. For this purpose a tissue array material of 114 colorectal cancer patients was obtained. In addition to the routinely used proliferation marker Ki-67, the analysed proteins included securin and CDC25B.

Processes such as cellular defense, cell structure, motility and cell division were found to be notably represented among the most deregulated genes. A significant portion of the overexpressed genes included those functioning in the cell cycle. Immunohistochemical stainings of securin and CDC25B showed a consistent expression pattern with that of cDNA microarray analysis. There was no statistical association between the studied proliferation markers and survival. Instead, there was a significant association between the Dukes' class and the histological grade (p=0.04), but not between histological grade and survival. The survival of Dukes' B patients was significantly poorer if no regional lymph nodes were studied compared with the Dukes' B patients with even a single lymph node was studied (p=0.04, hazard ratio 2.7).

Tumour stage is superior in estimating the prognosis of patients with colonic cancer compared with the grading of cell cycle regulators or histological grade of the cancer. The study of regional lymph nodes is essential to identify the patients who would benefit from adjuvant chemotherapy.