Prognostic value of pathological characteristics of colorectal cancer.

The overall cure rate of colon cancer has not improved dramatically in the last decade, remaining at approximately 60% 5-year survival. The main reason for this lack of progress is that at the moment the primary tumour is resected, a significant proportion of the patients with seemingly localised disease already has (undetectable) micrometastases, mostly in the liver. The most important prognostic indicators have been extension of the tumour into the bowel wall and the presence of lymph node metastasis, as expressed in the Dukes classification. However, in the Dukes B and C categories, these parameters are poor predictors of final outcome. For improvement of the prognosis, in addition to earlier detection, more aggressive (adjuvant) treatment of high risk patients would be a rational strategy. This requires development of new therapeutic modalities, but also reliable stratification of patients according to high risk or low risk for recurrent disease. In recent years, many attempts have been made to improve the prediction of final outcome. Parameters studied include inflammatory response to the primary tumour, tumour cell growth fraction, tumour cell differentiation, genetic abnormalities and expression of genes involved in invasion and metastasis. Although some of these newer parameters have significant predictive value, in multivariant analyses, most appear to have limited independent value. Recent studies indicate that genetic abnormalities might be important new prognostic indicators. One of the most promising findings in this area is an allelic loss of chromosome 18q, which allows division of Dukes B patients into subgroups with low risk and high risk for recurrent disease.