Clinicopathological and gene expression examination of young colorectal tumor patients

Introduction: In the colorectal tumorgenesis various genetic pathways are considered important in different age groups. In the view of prognosis, VEGF, GRP78 protein positivity among others seem to have overriding importance. Aims: We compared the gene expression profile of colorectal tumor patients under the age of 55 with data from previous studies. We also try to find the connection between the gene expression profile and the tumor invasion.

Methods: In the period of 1995–2005 we had 152 colorectal tumor patients younger than 55 years. 71 of them were suitable for tissue array technique and statistical analysis. The following parameters were investigated: grade of differentiation, tumor staging, lymphovascular invasion, perineural spreading, peritumoral inflammation, necrosis, desmoplastic reaction and the gene expression profile of p53, MMS, β-catenin, oestrogen, cyclin D1 and VEGF.

Results: We found the occurrence of β-catenin nuclear immunopositivity higher in the young colorectal tumour patients than in the literature (30% vs. 50%). The incidence of the other gene expression markers was the same in our young and in the old population. β-catenin positivity showed a significant correlation with the tumour progression and lymphatic spreading. We revealed microsatellite instability in 3 cases. We could not detect oestrogen receptor positivity. Marked positivity of p53 was found in tumour specimens, which refers high gene instability.

Conclusion: Our study also shows that in young patients the dominating colorectal carcinogenesis pathway is APC mediated. On the other hand, the incidence of microsatellite instability is under our expectations. These findings support the prognostic value of β-catenin nuclear immunopositivity in young patients.