Are there several types of colorectal carcinomas? Correlations with genetic data.

Abstract

Molecular studies have shown that different genetic pathways are involved in the history of colorectal carcinomas. This suggests that a correlation exists between the molecular, clinical and pathological features of tumours. Two large groups can be individualized: the first group is characterized by allelic losses and hyperdiploidy. These LOH (for loss of heterozygosity)-positive tumours represent 80% of colorectal carcinomas. Among them more than two-thirds are located in the distal colon. They have the worst prognosis. The second group has a normal diploid pattern and a phenotypic microsatellite instability without allelic losses. These tumours represent 10-15% of all colorectal carcinomas and about 30% of the right-sided tumours. They are associated with a better prognosis. In the future, it would perhaps be better to classify colorectal carcinomas according to their molecular features rather than to their topographical localizations.