Is mucinous carcinoma of the colorectum a distinct genetic entity?

Mucinous carcinomas are defined on the basis of the amount of the mucus component in the tumour mass. Apart from this quantitative criterion, a number of clinicopathological parameters (such as localisation, prevalence in different countries and age groups, association with HNPCC and inflammatory processes) and genetic alterations (e.g. frequency of mutation in Ki-ras and p53 genes, level of MUC2 expression) differentiate these tumours from the non-mucinous ones. Since a different set of genetic lesions implies different inducing agents, these observations suggest that there may be a 'mucinous pathway of carcinogenesis'. Further identification of genetic changes characteristic of the mucinous phenotype will help to understand the aetiology of these tumours and possibly establish markers for detection of the high-risk group.